Second progress report: year 1

Transcription

Project n° EVG1-CT-2000-00026 SESAME
European Commission – Research General Directorate
SESAME
Site EffectS assessment using AMbient Excitations
Second progress report
1 May 2001 – 30 April 2002
SESAME Partnership
1
2
3
4
5
6
7
8
9
10
11
12
13
14
UJF
Resonance
UP
ULg
UiB
ETHZ
ITSAK
ICTE/UL
INGV
CNR.GSAQ
GPISAS
CETE.Nice
CNRS
LCPC
University Joseph Fourier
Résonance Ingénieurs-Conseils SA
University of Potsdam University of Liège
University of Bergen
Polytechnic School of Zürich
Institute of Engineering Seismology and Earthquake Engineering
Institute of Earth and Space Sciences
National Institute of Geophysics and Volcanology
National Research Counsil
Geophysical Institute – Slovak Academy of Sciences
Center of Technical Studies
National Center for Scientific Research
Central Laboratory for Bridges and Roads
Co-ordinator: Pierre-Yves BARD - LGIT, Observatoire de Grenoble, BP 53
Signature of the co-ordinator:
Grenoble
Geneva
Potsdam
Liège
Bergen
Zürich
Thessaloniki
Lisbon
Roma
Milano
Bratislava
Nice
Grenoble
Paris
- 38041 Grenoble Cedex – France
SESAME, Progress report : may 01 – april 02
Content
Introduction ................................................................................... p. 3
Progress of the work ..................................................................... p. 4
WP01 – T01.01: co-ordination – year 1
WP02 – T01.02: H/V technique – experimental conditions – year 1
WP03 – T01.03: H/V technique – data processing – year 1
WP04 – T01.04: H/V technique – empirical evaluation – year 1
WP05 – T01.05: instrument layout for array measurements – year 1
WP06 – T01.06: array measurements – derivation of dispersion curves – year 1
WP07 – T01.07: array measurements – inversion of velocity profile – year 1
WP08 – T01.08: nature of noise wavefield – year 1
WP09 – T01.09: numerical simulation of noise – year 1
References
p. 5
p. 8
p. 9
p. 16
p. 21
p. 22
p. 25
p. 27
p. 29
p. 31
Sesame synopsis ......................................................................... p. 33
Co-ordination
Scientific and technical achievements
Dissemination of results
p. 33
p. 35
p. 36
SESAME important dates ........................................................... p. 37
Annexes ...................................................................................... p. 38
Minutes of the meetings or workshops
Presentations to International conferences
Papers
Deliverables
Others
Co-ordinator:
Pierre-Yves BARD
LGIT, Observatoire de Grenoble
BP 53
F-38041 Grenoble Cedex
Project n°EVG1-CT-2000-00026 - SESAME
p. 38
p. 38
p. 41
p. 41
p. 41
tel: +33 (0)4 76 82 80 61
fax: +33 (0)4 76 82 81 01
e-mail: [email protected]
Page 2
Introduction
April 2001
1 May 2001
May 2001
June 2001
26-27 June 2001
July 2001
August 2001
29-30 August 2001
September 2001
October 2001
22-26 October 2001
November 2001
December 2001
January 2002
7-8 January 2002
9-11 January 2002
February 2002
March 2002
April 2002
21-27 April 2002
signature of the contract between the partners and the European
Commission
ë beginning of the contract
⎤
⎥
⎥
ë Kick-off meeting in Grenoble, France
⎥
⎥ Work on the field and in
⎥ the laboratories on the
ë workshop for TaskC in Zurich,
⎥
different Tasks
Switzerland
⎥
⎥
⎥
ë Instrument workshop (TaskA – WP02) in ⎥
Bergen, Norway
⎦
a first progress report has been sent to the EC
⎤
ë Instrument workshop (Task A – WP02)
in Postdam, Germany
ë workshop (TaskA – WP03 & TaskBWP06) in Postdam, Germany
ë TaskA meeting during the EGS in Nice,
France
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎦
Work on the field and in
the laboratories on the
different Tasks
Preparation of the second progress report
SESAME project rules
1.
All the data lent by one of the SESAME project partners can only be used within the
framework of the project SESAME. If one partner wants to use the data for an other
purpose, it is essential that he asks for an utilization agreement to the data owner.
2.
Each time the SESAME project partners make a presentation concerning the project
SESAME, they must inform the co-ordinator of the project and as much as possible send
a copy of the presentation. Moreover, each presentations on the SESAME project have
the mandatory obligation to acknowledge the EC funding and mention the grant
identification.
Page 3
Progress of the Work
The following table shows the time table of the SESAME project. We have highlighted in yellow the work
which was planned to be in progress – and effectively is - at the date of April, 30, 2002
TABLE : Project planning and time table
Phases
WP
Tasks
P01
WP01
T01.01
T02.01
T03.01
P02
WP02
T01.02
T02.02
WP03
T01.03
T02.03
WP04
T01.04
T02.04
T03.04
P03
WP05
T01.05
T02.05
WP06
T01.06
T02.06
T03.06
WP07
T01.07
T02.07
T03.07
P04
WP08
T01.08
T02.08
WP09
T01.09
T02.09
WP10
T01.10
T02.10
P05
WP11
T01.11
WP12
T01.12
WP13
T01.13
Year 1
Year 2
Year 3
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
Deliverables of
Year 1
D03.01
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxx
xxxxxxxxx
xxxxxx
xxxxxx
xxxxxxxxxxxx
xxxxxx
xxxxxx
D01.02
xxxxxx
xxxxxxxxx
xxxxxxxxx
xxxxxxxxxxxx
xxxxxx
xxxxxxxxxxxx
xxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxx
xxxxxx
xxxxxxxxxxxx
xxxxxxxx
xxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxx
xxxxxxxx
xxxxxxxxxxxx
xxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxx
xxxxxxxxxxxx
xxxxxxxxxxxx
D02.09
xxxxxxxxxxxx
xxxxxxxxx
xxxxxxxxx
xxx
xxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
xxxxxxxxxxxx
Page 4
I
WP01 – T01.01: co-ordination – year 1
The co-ordination is followed by two persons:
Pierre-Yves Bard for the scientific part and Laurence Bourjot for the administrative and financial part.
During the first year, 61 persons have been involved in the project SESAME for a minimum of 108,06 manmonths: 38 researchers or engineers, 10 students, 12 technicians and 1 assistant-coordinator (Table 1)
All these persons have meet several times to exchange their work and also to do experiments together.
ë
26-27 June 2001 - Kick-off meeting in Grenoble (France):
•
•
•
•
ë
29-30 August 2001 – Task C meeting in Zürich (Switzerland):
•
•
•
•
•
•
ë
to present the existing processing software,
to discuss about the basic structure of the SESAME software.
20-21 March 2002 – TaskC-Meeting in Bratislava (Slovakia):
•
•
•
ë
to set the final work that has to be done to write the final report concerning Instrument workshop (Bergen Oct
2001).
9-11 January 2002 – TaskA-WP03 Workshop in Postdam (Germany):
•
•
ë
to investigate the influence of different instruments in estimating the local site response using H/V technique on
microtremor data. There were 4 major tasks performed during the workshop, which consisted of testing the
digitizers (Task 1), sensors (Task 2), simultaneous recordings both outside in the free-field (Task 3) and at the lab
(Task 4) for comparisons. In addition, an initial test data (Task 0), were also collected to provide individual noise
data sets for each system.
7-8 January 2002 - Instrument Workshop (TaskA-WP02) in Postdam (Germany):
•
ë
to review the modelling experience and available numerical tools for modelling seismic noise,
to look at available computing facilities,
to define seismic noise generation,
to define canonical models of local surface geological structures,
to plan future meetings of TASK C,
to review the available methods of the time-frequency analysis.
22-26 October 2001 – Instrument Workshop (TaskA-WP02) in Bergen (Norway):
•
ë
to recall the general administrative and scientific frameworks of this project,
to recall the main objectives of each task and work packages,
to agree on immediate actions (next months to first year),
to establish a tentative schedule for the whole duration of the project (especially for meetings dates and locations).
to revise canonical models and the algorithm for seismic noise generation
to discuss noise simulation for the Colfiorito and Grenoble valleys
to discuss the publishing of the project results
21-27 April 2002 – Task A meeting in Nice (France)
•
•
•
to discuss about the instrument influence on H/V ratio (WP02). The partners have presented the results they
obtained with their own experiment and their own process for the test they performed. Then, for each parameter,
preliminary conclusions were drawn. A time table for work was established: to attribute to each team the test that
are still needed, to define a common data format, to have an agreement for the principle of a common process and
make clear the dead-lines;
to discuss about the software development (WP03) and in particular on the two modules: (i) Main Processing
Module and (ii) Display Module;
to present and discuss the available data on Existing Ambient Noise & Earthquake Recordings (WP04), and to see
which data has to be acquired on Ambient Noise Recordings.
Page 5
The minutes of the different meetings or workshops are available on the web site:
http://SESAME-FP5.obs.ujf-grenoble.fr
During this first year, the partners, in parallel to their work on the project, have participated to different national
or international meeting where they have presented a part of the scientific work done in the SESAME project.
ë
AGU in San Francisco (USA), 10-14 December 2001: presentation of a poster by Matthias Ohrnberger
M. Ohrnberger, F. Scherbaum, K.-G. Hinzen, S.-K. Reamer & B. Weber – Vibrations on the roll-Mana, a roll along
array experiment to map local site effects across a fault system.
ë
Assemblea Hispano-Portuguesa de Geodesia y Geofisica in Valencia (Spain), 4-8 Feb 2002: presentation
of a communication by Paula Teves-Costa
P. Teves-Costa, C. Riedel, J.L. Gaspar, D. Vales, G. Queiroz, M.L. Senos, N. Wallenstei, F. M. Sousa e M. Escuer Ensaios para a interpretação de anomalias de intensidades sísmicas nos Açores: estudos de ruído ambiental no
Concelho da Povoação (ilha de S. Miguel) - Tests for the interpretation of seismic intensities anomalies at the
Azores: Microtremor survey on Povoação County (S. Miguel island)
ë
EGS meeting in Nice (France), 21-27 April 2002: presentation of a poster by Bertrand. Guillier.
B. Guillier, K. Atakan, A-M. Duval, M. Ohrnberger, R. Azzara, F. Cara, J. Havskov, G. Alguacil, P. Teves-Costa,
Nikos Theodulidis and the SESAME Project WP02-Team – Influence of instruments on H/V spectra of ambien
noise.
ë
EGS meeting in Nice (France), 21-27 April 2002: presentation of a communication by Paula Teves-Costa.
P. Teves-Costa, C. Riedel, D. Vales, N. Wallenstein, A. Borges, M.L. Senos, J.L. Gaspar, G. Queiroz – Microtremor
survey on Povoação County (S. Miguel island, Azores): data analysis and interpretation.
The summary of the different communications and posters are presented in the annexes of the report p. 38
Page 6
TABLE 1 : List of the persons working in the project since the beginning
Partners
1
1
1
1
1
1 (13)
1 (13)
1 (13)
1 (14)
1 (14)
2
2
2
3
3
3
4
4
5
5
5
5
5
5
6
6
6
6
6
6
7
7
7
7
7
7
7
7
7
8
8
8
9
9
9
9
9
9
9
10
10
10
10
10
10
11
11
11
11
12
12
Name of the person
Bruno Bettig
Fabien Blarel
Sylvette Bonnefoy
Laurence Bourjot
Fabrice Cotton
Jean-Luc Chatelain
François Dunand
Bertrand Guillier
Pierre-Yves Bard
Philippe Guéguen
Martin Koller
Corinne Lacave
Julien Rey
Matthias Ohrnberger
Frank Scherbaum
Daniel Vollmer
Denis Jongmans
Marc Wathelet
Kuvvet Atakan
Margaret Grandison
Jens Havskov
Bladimir Moreno
Eirik Tvedt
Terje Utheim
Gerardo Aguacil
Cécile Cornou
Donat Faeh
Francesca Bay
Fortunat Kind
Ivo Oprsal
Jochen Woessner
Nikolaos Adam
Anastasios Anastasiadis
Petros Dimitriu
Apostolos Marinos
Bassilios Margaris
Areti Panou
Nikos Theodulidis
Eleftherios Vorias
Stratos Zacharopoulos
Antonio Borges
Pedro Roquette
Paula Teves-Costa
Catello Acerra
Riccardo Azzara
Fabrizio Cara
Giovanna Cultrera
Giuseppe di Giulio
Sandro Rao
Antonio Rovelli
Rosastella Daminelli
Roberto de Franco
Alberto Marcellini
Antonio Morrone
Marco Pagani
Alberto Tento
Lucia Fojtikova
Josef Kristek
Miriam Kristekova
Peter Moczo
Anne-Marie Duval
Sylvain Vidal
•
Task or WP
S
T
S
ACo
R
R
S
R
R
R
R
R
R
R
R
T
R
S
R
S
R
S
S
T
R
R
R
R
R
R
R
T
R
R
T
R
S
R
T
T
S
R
R
T
R
R
R
R
T
R
T
R
R
T
R
T
S
R
R
R
R
T
WP 06
WP 02
WP 08
WP 01
WP 08
WP 02
WP 02
WP 02
WP01, Task A,C
WP01, WP02
WP01, WP03
WP01, WP03
WP 03
WP 02, TaskB
Task B
WP 02
TaskB
WP07
Task A
WP 02
Task A
WP02, WP03
WP02, WP03
Task A
Task A
Task A, C
Task A, B, C
Task A, C
Task A, B
Task C
Task A
WP02, WP04
WP02, WP04
WP02, WP04
WP02, WP04
WP04
WP04
WP02, WP04
WP02, WP04
WP02
WP02,WP03,WP04
WP03
WP02
WP02
WP02
WP02, WP04
WP02, WP04
WP02, WP04
WP02
WP02, WP04
WP03, WP04
WP04
WP03, WP04
WP04
WP04
WP03, WP04
Task C
WP 09
Task C
Task C
WP02,WP03,WP04
WP02
Time spent
4M
0,7 M
8M
1,3 M
0,8 M
1,7 M
0,25 M
5,15 M
4,5 M
2M
0,45 M
0,43 M
0,79 M
12 M
AC
AC
AC
6M
AC
0,44 M
AC
1,42 M
2,67 M
AC
AC
1M
AC
1,5 M
4M
AC
AC
AC
1M
2M
AC
0,5 M
1M
8,3 M
AC
1M
7M
2,25 M
AC (4,6 M)
AC
AC
6M
AC
AC
AC
AC
0,32 M
0,15 M
0,27 M
0,16 M
2,44 M
0,83 M
2,4 M
0,99 M
2,7 M
4,3 M
1,85 M
R = Researcher, S = Student, T = Technician, ACo = Assistant Coordinator
Page 7
II
WP02 – T01.02: H/V technique – experimental conditions – year 1
Leader : Anne-Marie Duval (Partner 12 : CETEMED.LRE – Nice – France)
The aim of WP02 is to evaluate the influence of experimental parameters in stability and reproducibility of
“H/V on ambient vibrations”. This means that we have to test various type of parameters and to check the
variations both in frequency and in amplitude of the “H/V curves”. One of the numerous parameters to test (the
recording instrument in itself) has been evaluated separately during this first year under the main direction of
UiB.ISI (Bergen, Norway). The other parameters are tested in a common and global survey performed
simultaneously by all partners. During the first year, this WP was divided into two parts: the influence of the
instrument in itself and (simultaneously), the influence of all other experimental parameter.
1. The influence of the instrument in itself on H/V on ambient noise
•
After the kick off meeting (May, 2001), each team had to prepare the “SESAME instrument workshop”:
listing the instrument available for each team, choosing which instrument had to be evaluated, gathering
specifications from the manufacturer.
•
In October 2001, the “instrument workshop” took place in Bergen (UiB.ISI, Bergen - Norway) where an
intensive experimental evaluation has been performed. A great amount of data was collected by each team.
Individual measurements were performed as well as common experiments following protocols set up by
UiB.ISI Bergen. Each team wrote a preliminary report during this workshop. (see Bergen Meeting WP02
minutes)
•
After the workshop, partners had to gather their individual results in a preliminary common report concerning
the instrument evaluation.
•
A SESAME workshop was organized in Potsdam (Germany) in early January. One day and half were
devoted to the instrument evaluation. The aim was to take stock on this evaluation and to share the work to
produce the final report. We decided to affect the responsibility of each chapter of the final report to specific
persons (see Potsdam Meeting WP02 minutes). Additional experiments were required to each team (in their own
laboratory) to produce data needed for evaluation. Many other decisions were taken to achieve the
comparison of instrument. We had to improve the data processing in order to fit as much as possible our aim.
For instance, as SEISAN software was chosen to process “instrument” data, Bergen UiB.ISI partner
(SEISAN designer) was asked to adapt SEISAN software to the required process. The calibration files of
each instrument had also to be checked to progress in the instrument comparison.
•
During February 2002, most of the required added data were collected and gathered.
•
During March 2002, SEISAN software and calibration files were adapted, all the data set could be processed
in a common way.
Another SESAME workshop was organized in Nice in April 2002 (see Nice meeting minutes). During the first 2
days of this workshop, the persons implied in the final process of the instrument data gathered their results. A
poster was produced and presented during EGS meeting in Nice (2002, April the 23rd- see EGS 2002 poster). The
last process and graphs to complete the final report were produced. Then the final report was written. It is the
first deliverable D01.02 “Controlled instrumental specifications” of the SESAME project.
2. The influence of the other experimental parameter
•
Although the time spent for “instrument” comparison has been quite large, “recording instrument” is only one
of the numerous experimental parameters that can have an influence on the “H/V on ambient vibration”
curves, as was already emphasized during the kick off meeting.
•
That is why, immediately after this SESAME kick-off meeting, all partners had intensive exchange to:
− make clear the problem to solve,
− prepare an exhaustive list of experimental parameter to test,
− design the surveys,
− set common and strict experimental protocol,
− define common forms to be filled to build a common data base,
− share the instrumental work.
Page 8
•
Many documents were established and regularly updated to take into account new remarks.
•
During the Potsdam SESAME meeting (2002 Jan the 5th), we agreed to work following the directions
described in several documents:
− list of parameter to test (file: “directions.WP02.v3.doc”),
− direction for use (also included in the file: “directions.WP02.v3.doc”),
− excel file forms to be filled for each record (file: “team.parameters.vX.xls”),
− data base design,
− a table was established to summarize tests that had to be performed by each partner following the former
procedures.
In February, Nice (CETEMED.LRE) and Grenoble (UJFG.LGIT) partners had a meeting to detail more
precisely their own tests (file: Grenoble-Nice.testWP02.v1.doc).
•
•
During February and March 2002, each partner performed several tests, processed the results with their own
software and noted all experimental conditions as required. It has to be noticed that the required tests are very
numerous and time consuming. Furthermore, some of them can not be performed at any time. This is the case
for instance for the test concerning the influence of the water table, or the weather. That is why many tests
were not completed in April 2002.
•
Another SESAME workshop concerning this task was organized in Nice the 23rd and 24th of April 2002 (see
Nice meeting Minutes). This meeting aimed at:
− checking the result of the tests already performed,
− deciding which tests are needed after these first results,
− attributing these tests to each team,
− organizing the data processing,
− plan the work to be done until the final report.
During the meeting, all partners presented first the results obtained with their own experiments and their own
process for the tests they performed during the previous weeks as planned in Potsdam (Germany) in January
2002. For each parameter, preliminary conclusions were drawn.
To conclude a planning of work was established:
ë to attribute to each team the test that are still needed,
ë to define a common data format (in relation with WP03-sofware),
ë to have an agreement for the principle of a common process and make clear the dead-lines.
☺ Up to now, the time table is respected and there is no problem. A first deliverable has been produced D01.02
“Controlled instrumental specifications” in the form of a report. The next step will be the deliverable D08.02
“Measurement guidelines” for November 2002.
III
WP03 – T01.03: H/V technique – data processing – year 1
Leader : Kuvvet Atakan (Partner 5: UIB.ISI – Bergen – Norway)
In the following, we summarize the status of the WP03 dedicated to development of a multiplatform H/V
software. The status was discussed during the meeting at CETE-Nice, France, 26-27 April 2002 and the details
can be found in the minutes.
During the Potsdam meeting in January 2002, it was considered mandatory that this software be really usable in
any part of the world on any platform. As a consequence, the software is designed as two separate modules (i) a
Main Processing Module written in Fortran, and (ii) a Display Module written in Java. Since that time, the work
regarding the first module was then organized and performed by the ETHZ-Zurich and CNR-Milano groups,
whereas for the latter module, the work was organized and performed by the ICTE/UL-Lisbon group. Further
work will be coordinated between the UiB-Bergen and the ICTE/UL-Lisbon groups regarding the integration of
the display modules into the browsing and the graphical user interface. A preliminary design of the graphical
user interface and the browsing modules has been performed, and is given in the following. In addition, an
automatic window selection routine will be integrated to the browsing routine. This will require that the window
selection routine of the LGIT-Grenoble group will be modified and adopted to the browsing part of the
software. LGIT-Grenoble and the UiB-Bergen groups will coordinate the implementation of this.
Page 9
1. Graphical user interface and the browsing module
It was suggested that the browser module would organize groups of files in a project file. The organization is
made interactively, and the project file created.
Following is a synthetic list of the most common usage scenarios that were identified.
Usage Scenario 1 – creating a new project
SESAME
Project
You create a new project by using the option
in the menu (Figure 1).
Config
Process Help
New
Open
Close
Save
Save As
Insert Data File
Figure 1
Print
Exit
Then the windows
changes to include the
project tree (Figure 2).
Figure 2
The user should then use the menu
(Figure 1) and insert the files (in GSE
–CM6 or SESAME ASCII format
‘SAF’) that will be used in this project
(one can repeat this operation as often
as desired, to take files from several
different places). (Figure 3).
Figure 3
Page 10
The files go into a general group, the unassigned files group. It is the place where the user leaves its files if
he/she wants to process single files, which means that one-file represent one-site.
Next, the user can organize its files in groups (sites). This can be done by using the group by code button – it
will read the file header and create groups based on the site id information – or he/she can organize them
interactively by creating site nodes (using the new site button) and dragging files from one group to the other.
Grouping can also be done using the code from the file-name (i.e. the first 6 characters).
The user has the possibility to eliminate a site node or a file node – using the delete button. When the user
eliminates one site the files that it owns go into the unassigned group again. When the user eliminates one file
from the project it is deleted from the tree.
Once the project is structured the user can save it, using the corresponding menu option.
To make changes to a project already built the user opens the project and makes the necessary changes – add
new files, delete files, reassign files to sites, … - and then he saves the project again.
Usage Scenario 2 – data preview and window selection
SESAME
Project
Config
Processing
# of
windows
Project
The user can preview the data
in the project by selecting the
data file in the tree. The data
is shown in the right panel
(Figure 4).
Help
Window
length
Output file
name
Unassigned files
File 1
File 2
Site 1
File 1
File 2
File 3
Site 2
File 1
File 2
Figure 4
Group by code
Add new site
Delete
The user can select more than one file to preview them together. If there are time windows associated with the
data – already calculated by the automatic windowing module or selected manually by the user – the time
windows are shown.
The user can also define time windows interactively, if he selected manual window selection in the config menu
(Appendix A - p. 12). When the user clicks the mouse on the time series a window is added, with the project
default window length. When the user presses and drags the left mouse button on the time series, the browser
will calculate the number of windows to define and adds those windows in the interval defined with even
spacing. By using the right mouse button the user accesses a popup menu with which he can choose to delete the
selected window or all windows.
Usage Scenario 3 –processing the files in a project
After having configured the window selection and input parameters (or at least confirmed the acceptance of the
default values) the user can process the project files. He/she selects the process menu option and the browser
calls the processing routines.
If the processing runs without problems the browser calls the display modules to allow the user to view the
results from the processing. If the processing produces a warning or an error the browser displays the resulting
log file.
In the simplest of scenarios the user opens a project already created and just selects the process option. If
desired the user can review and change the window selection and the processing parameters (by calling the
config menu- Appendix A).
Page 11
SESAME
File
Config
Process Help
- Appendix A: Screen snapshots -
Window selection
Input parameters
2. Main Processing Module
Status of the work
A preliminary version of the main processing module is developed by the ETHZ-Zurich and CNR-Milano
groups in a coordinated effort. Two meetings were held in Milano during the 14-15 March and 18-19 April 2002
for the coordination of the work. Otherwise, the work was performed individually by each group, and the
information was exchanged electronically. The first approach of a command line module is finished, processing
a set of default parameters. Not all options are yet included, tested platforms are currently Windows-PC and
Linux. Currently only the Cityshark data format is read, GSE is not yet ready. Further development will
continue during May and June and it is envisaged that the first test version of the main module will be available
for the participants by the end of June 2002. It will be possible to have comments, suggestions and the report of
possible bugs until mid-September 2002.
Information about the processing options and the different files (parameter file and the output files) can be
found in the Nice meeting minutes.
The current version of the main processing module works through the following command line call:
hvproc0_1 winfile parfile outfile defparfile
The instrumental correction is requested to be included, such that the spectra written out for the single window
output are meaningful and can be included into publications.
An agreement is reached that the processing of multiple sites is steered through the browsing module and not
the main processing module.
Page 12
Window input files ("winfile")
example of window file:
/home/acmt/HVtest/Mt/12121112.tst
/home/acmt/HVtest/Mt/12120826.stc
5 25 one two thr
15 35 one two thr
30 55 one two thr
30 59 one two thr
39 59 one two thr
Blank-lines and blanks at any location do not matter. Comment lines beginning with a ‘#’ character are ignored
as well. The two numbers after the file names represent the index of the samples at the start of the window and
at the end of the window.
The format of the window file is kept like this strictly. The processing of multiple sites has to be done through
some form of batch processing, steered from the browser module.
The window length in the window file is defined as being fixed as an input parameter to the window selection.
The anti-trigger method has this implied already, for the manual window selection a ‘post-windowing’ should
be implemented, subdividing long time windows into windows of the fixed length (with some optional overlap).
Parameter file ("parfile")
A major change is that currently the error estimates are only the standard deviations – arithmetic averaging – or
the log-standard deviation – in case of logarithmic window averaging.
Output files ("outfile")
They contain the window specifications (window file), the parameter definitions and the output data.
More details concerning all these files (Parfile, Outfile as well as Defparfile – Default parameter files) are given
in the minutes of the Nice WP03 meeting available on the web sites http://SESAME-FP5.obs.ujf-grenoble.fr.
Format of the input waveform file: SESAME ASCII
It had been agreed that two forms of data files are to be used; GSE and a specific SESAME ASCII format. The
SESAME ASCII format will be structured into a header, separated from the data by a line of the type:
####------------------------------------------As the data has to be converted anyway, the definition of the format can be arbitrary. For simplicity the ‘Pitsa’
codes should be used as much as possible. But each information is put on a separate line.
The data arrangement will be in 3 columns, strictly in the order Vertical, NS, EW.
The following keywords/codes should be available from the header:
− site code of exactly six characters (eg. BSL_12),
− sampling_rate in Hertz (eg. 125Hz),
− date and time: start time of the trace as accurate as possible,
− accuracy of timing,
− acquisition system,
− instrument-ID digitizer (serial number),
− sensor type (accelerometer/seismometer),
− instrument-ID sensor (serial number),
− reference code of the sensor response (instrument response file),
− conversion factor: counts -> Volt (V/count),
− transduction: Volt -> physical meaning (V/m/s),
− units of data in file (counts, or whatever, just identifying it),
− number of data points,
− comment line defining Vertical, NS, EW,
− saturation of digitizer,
− Station coordinates on separate lines, X,Y,Z,
− project name,
− arbitrary number of comment lines,
Page 13
−
−
separator line before the data,
earthquake information as defined for the Pitsa format.
In general the processing should be possible without most of the above information. But the following are
strictly required:
− sampling_rate in Hertz (eg. 125Hz),
− number of data points,
− channel information is needed, but it is fixed in the format.
The following two options are of interest for the processing and it is highly desired to have them in the data:
− reference code of the sensor response (instrument response file)
− saturation of digitiser in units of data
The remaining options are recommended. Additional codes should be possible but ‘Pitsa’ codes are strongly
recommended and additions of codes should be used very restrictively.
Filenames of SESAME ASCII
Free file name, extension of the name will be .saf, such that the format can be identified from the extension.
The suggested filename contains site code (6 characters), date and time: NNNNNN_yyyyMMdd_hhmm.saf
Response file
The instrument response is in a separate file, in a default directory of the installation. The header contains a
reference to the response file. The response contains the response of the sensor. The format of the response file
is taken from ‘Pitsa’ or GSE.
The name of the response file is the name of the instrument, as defined in Xpitsa, the same codes are used, and a
default directory belongs to the installation of the H/V software, where the response files are stored. The
developers decide on the format of the response file so as to minimize the work amount to include the
instrument correction.
3. The Display Module
The status of the ‘Display Module’ was summarized by the ICTE/UL Lisbon group. During the preparations
interactions were made with groups working on the main processing module to coordinate the data input and
output. The preliminary version of the display modules were developed as agreed on the Potsdam meeting and
presented. The developments were done in Java code. In the following, summary of the suggestions made
during the meeting, as well as the snapshots of the different graphical displays are given (Appendix B – p.16).
−
−
−
−
−
−
−
−
In the output window (Ap. B-1) the title used will be the name of the output file.
In the output window (Ap.B-1) we should show all processing parameters present in the parameter file.
In the time series window (Ap.B-2) we should include the start time.
Place a button in all of the windows to open the HTML version of the manual (to be written within Task D).
Possibility (by pressing a button) to show the header of the input file.
Show a legend with the meaning of each of the curves.
It should be possible to change the settings of each chart. The settings include: - the colors, - the line patterns
and thickness, - showing (or not) the chart gridlines, - showing (or not) box axis, - the font properties of the
various fonts, - which curves to show.
The windows should be resizable.
Options that are being implemented
•
•
User option to change between logarithmic and linear scales. The user will also be able to change the
limits in the scale
Possibility to show the wave graphics using a common vertical scale or one scale for each component
(Ap. B-2). This will be accomplished using a check box which will link/unlink the scales
The suggestions for improvements from the participants will be made until June 15, 2002.
Page 14
- Appendix B: Snapshots of the Display Module Parameters window:
This window is being discussed
by the three development teams
as to which parameters should be
used, the default values to be
used in each case, as well as the
limits of each parameter.
Ap. B-1 - Graphic window (output
window): the title used will be the
name of the output file
Page 15
Ap. B-2 - Graphic window (time series window): the start time should be included.
☺ In general the progress is satisfactory and the further actions are scheduled to be done until October 2002, in
order to discuss them during the project meeting that will take place in Rome. The deliverable D09.03 “Multiplatform H/V processing software” is thus still foreseen for February 2003.
IV
WP04 – T01.04: H/V technique – empirical evaluation – year 1
Leader: Nikos Theodulidis (Partner 7 – IESEE – Thessaloniki – Greece)
This work package is intended to perform an objective, purely experimental assessment of the reliability of the
H/V technique, by comparing its results with those of other, well established experimental techniques, based on
a homogeneous data set of ambient noise and earthquake recordings. It will also compare H/V results with
observed damage on recent earthquakes.
During the period November 2001 to April 2002 each Partner participating in WP04 prepared an inventory of
all the existing data sets, both for ambient noise and earthquake recordings at the same site. A preliminary
catalogue of this data was sent to the WP04 leader and all data was presented at the SESAME-Nice meeting on
April 25th, 2002. In that meeting the data presented in Appendix A (p. 18) were decided to be used for further
analysis according to the project. The data format of all the data sets (ambient noise, earthquake recordings) was
decided to be either SESAME–ASCII or GSE-ASCII. Parallel to the aforementioned, all Partners have
performed or will perform in the next few months additional ambient noise measurements at selected sites in
order to enhance the existing data set.
In addition, a few damaged cities - mainly in Greece and Italy - will serve as experimental sites where ambient
noise measurements have been performed or will be performed in order to compare them with damage
distribution. These sites are given in Appendix B (p. 20).
Page 16
For each experimental site a Standard Information Sheet was prepared and adopted by the Partners during the
Nice meeting, both for ambient noise data vs earthquake recordings (example is given in Appendix C-1, p. 20)
and ambient noise data vs damage levels (example is given in Appendix C-2, P. 21).
- Appendix A: available data (Earthquake & Noise Recordings) 1. ITSAK (Thessaloniki)
No
Site (Name/Code)
Ambient
Noise
Earthquake
Records -Weak:
vg or ag
Earthquake
Records -Strong: ag
≥0.1g
vp-vs-{Q}
N
N
N
N
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
N
Y
N
Y
N
N
Y
N
Y
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
01
Edessa[EDE]
02
Almiros[ALM]
03
Patra [PAT1]
04
Lefkas[LEF]
05
Kyparissia[KYP]
06
Argostoli[ARG]
07
Pyrgos[PYR]
08
Kozani[KOZ]
09
Kalamata[KAL1]
10
Kalamata[KAL2]
11
Kalamata[KAL3]
12
Euroseistest[STE]
13
Euroseistest[STC]
14
Euroseistest[FRM]
15
Euroseistest[TST]
16
Euroseistest[GRA]
17
Euroseistest[GRB]
18
Euroseistest[PRO]
19
Thessaloniki[OBS]
20
Thessaloniki[THE]
21
Thessaloniki[KAL]
22
Thessaloniki[POL]
23
Thessaloniki[TIF]
24
Thessaloniki[LEP]
25
Thessaloniki[LAB]
26
Thessaloniki[ROT]
27
Thessaloniki[AGO]
28
Thessaloniki[OTE]
29
Thessaloniki[AMP]
30
Athens[ALS]
31
Athens[MND]
32
Athens[FRN]
Available in the near future
33
Korinthos[KOR]
34
Zakynthos[ZAK]
35
Athens[ATH2]
36
Athens[ATH3]
37
Athens[ATH4]
Other Info
Reference
In addition there are ~35sites of ITSAK’s strong motion network:
−
strong motion recordings (weak & strong)
−
surface geology information
−
noise measurements (existing & in next months)
2. CSGAQ-CNR (Milano)
Fabriano data set
−
−
−
−
−
−
−
−
Umbria - Marche 1997 earthquake
Network installed in the urban area of Fabriano (~ 2 Km x 2 Km) (Marche region)
21 sites mainly on fluvio-lacustrine deposits (thickness < 30 m) except for two stations on outcrops of the Umbro-Marchigiana series
sensors : Mark L4C-3D 1 Hz, Mark L22-3D 2 Hz, Lennartz LE-3D 0.2 Hz
~ 40 events, 2.1 < ML < 4.6, 25 < hypocentral distance < 40 Km
2 Hz < F0 < 6 Hz
Noise recordings (10 minutes continuous) for 5 stations
Vs profiles up to 15 – 25 m available for 3 locations (down hole and SASW), nearest stations at ~ 250 m.
Nocera data set
−
−
−
−
−
−
−
−
−
Umbria - Marche 1997 earthquake
Two temporary arrays deployed in localities around Nocera Umbra (Umbria region).
13 and 10 sites respectively
All the stations with sensors Mark L4C-3D 1 Hz
~ 20 events, 1.5 < ML < 3.7, 5 < hypocentral distance < 40 Km.
4 Hz < F0 < 8 Hz
Noise recordings (10 minutes continuous) for 7 stations
Accelerometric site with main shocks recordings and velocimetric aftershocks recordings
Vs profiles up to 10 – 15 m available for 2 locations (down hole and SASW) near stations.
Page 17
Predappio ( Emilia Romagna region) data set
−
−
−
−
−
Weak motion recordings in 20 sites – shallow alluvial deposits (thickness<10m)
sensor Mark L4C-3D 1 Hz
Noise recording (10 minutes continuous) in each site
5 Hz < F0 < 12 Hz
Vs profile up to 15 m available in 1 station site (cross hole)
Noise recordings along seismic reflection lines
−
−
−
−
reflection profiles across glacial valleys in Valtellina and Val Seriana (Lombardia), - valley width ~ 1 Km, - bedrock depth ~ 300 – 400 m
Vp in fluvial and glacial deposits 700 m/s 2500 m/s, - Vp bedrock ~ 4000 m/s
Noise recording (10 minutes continuous)
Sensor Lennartz LE-3D 0.2 Hz
3. LGIT (Grenoble)
Site
Team
Hmax
(indicative)
Annecy
Ebron
Grenoble
Nice
Pointe-à-Pitre (Guadeloupe)
Thessaloniki (common with ITSAK)
Volvi 1997
LGIT
CETE
LGIT
CETE/LGIT
LGIT+ CETE
LGIT + AUTH
LGIT + AUTH
100 m
100 m
800 m
60 m
30 m
100 m
200 m
30-800 m
TOTAL
Amplification
Band-width
Range
1 – 10
1 – 10
0.3 – 5
1 – 10
1–6
0.5 – 10
0.7 – 10
0.3 – 10
Other data possibly available
Sites
alluvial
rock
4 - 10
10 - 20
5 - 20
8 - 20
5 - 15
3-8
4 - 12
3 - 20
3
3
9
4
4
8
5+10
46
2
2
2
1
2
2
1
12
Other experiments
RAP station pairs in
- Chambéry (2 sites)
- Guadeloupe / BRGM (?upon request)
- Lourdes (8 sites, shallow quaternary deposits)
- Tehran (10 sites, under way till June 2002)
- Mexico (Chavez-Garcia / Ordaz) (?upon request)
For each series of sites, both earthquake and microtremor recordings are available
4. INGV (Roma)
Sites
Noise
1
2
3
4
5
6
Benevento
Catania
Colfiorito
Verchiano
Città di Castello
Ferrara
Number of
stations
Site
1
2
3
4
5
6
Yes
Yes
Yes
Yes
Yes
Yes
Earthquake recordings
Velocity
Acceleration
≥0.1g
Yes
Yes
Yes
Yes
Yes
Yes
Recording
period
No
No
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Sensors
Geological or/and Geophysical data
LithoSPT
Vp
Vs
Q
logy
values
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Digital
acquisition
3
12/07/00-05/12/01
Lennartz 3d 5sec
MarsLite
6 (From Jan.02 8
stations at Ben)
7 (3 without GPS
information)
4 (3 in the middle of
basin, 1 at the edge)
basin, 1 on bedrock)
basin, 1 in the edge)
11 (6 channels), linear
array
7
27, linear array
since 05/12/01
Lennartz 3d 5sec
since 02/11/00
68 sites
Yes
No
Yes
No
Yes
Yes
ρ
No
No
No
No
No
Yes
Sample
frequency
Yes
No
No
No
No
Yes
Data
format
SAC-linux
MarsLite
31,25 (until 04/10/00)
62,5
62,5
17-24/02/98
Guralp
cmg40t – cmg5t 3d
Guralp cmg40t 3d
Reftek 72A0772A08
Reftek 72A07
50 (velocimeter)
100 (accelerometer)
100
24/02- 03/03/98
Guralp cmg40t 3d
Reftek 72A07
100
10-19/03/98
Guralp cmg40t 3d
Reftek 72A07
100
SEGY-Unix /
SAC- Unix
SEGY-Unix /
SAC – Linux
SEGY-Unix /
SAC - Linux
SEGY / SAC
Reftek
250
SEGY / SAC
Reftek
125
Lennartz 5800,
125
Lennartz Mars88,
Reftek 72A07
Reftek 72A07,
125
Lennartz 5800,
Marslite
Lennartz Mars88/FD62,5
SEGY / SAC
SAC- SEGY
20-24/10/97
L22
CMG40t 3d
19/5-4/6/98
Lennartz 3d 5sec
continuos recording 14- Lennartz 3d 5sec
25/05/2001
each 10 minutes
14-25/05/2001
12
7
No
Yes
No
Yes
Yes
No
Sratigraphy
Lennartz 3d 5sec
trigger recording
Mark L4C/3D
7/4-28/6/2000
7
trigger recording 28/6- Mark L4C/3D
5/12/2001
2 (1 at the surface, 1 in a 10/1996
CMG3 100s
borehole 130 m deep bedrock-)
SAC-linux
SAC- SEGY
Lennartz Mars88/FD62,5
Mars88/ Guralp
system
100 - 125
SAC
Among the mentioned sites, (1) Benevento, (3) Colfiorito and (7) Ferrara are well documented while the others are poorly documented.
Page 18
5. ETHZ (Zürich)
Swiss Seismological Service operates a network of 59 stations throughout the country. All of them belong to “poorly” documented sites
with respect to geotechnical / geophysical data. For about 10 sites, data from earthquake recordings and ambient noise measurements are
available and will be sent to WP04 leader.
In conclusion, there are two categories of sites: - well documented & Earthquake & Noise
- poorly documented (Surface geology) & Earthquake & Noise
It was proposed by P-Y. Bard - and accepted - that two additional sub-categories of earthquake data should be established,
namely: - well documented data with reference site,
- poorly documented data with reference site.
- Appendix B: available data (Damage & Noise Recordings) Sites
1. ITSAK (Thessaloniki) Thessaloniki
(20/6/1978, M6.5, R=30km)
2. INGV (Roma)
3. CETE (Nice)
Kalamata
(13/9/1986, M6.4, R=9km)
Athens Suburbs
(7/9/1999, M5.9, R<10km)
Roma
(Umbria-Marche 1997 earthquake)
Palermo
(destructive event of the 19th century)
Caracas-Venezuela
(Caracas 1997 earthquake)
Damage
Noise recording
Detailed Damage per Block
Equal Damage Map
Cost of Repair Map
Detailed Damage per Block
Equal Damage Map
Equal Damage Map
noise will be measured
Equal damage map of the city
Equal damage map of the
historical centre (3 levels)
Equal damage map of the city
- Appendix C-1: Ambient noise data vs earthquake recordings
noise may be measured ???
noise measurements already
done
(Standard Information Sheet for
each experimental site) -
Information
SITE [Name/Code/Coordinates]
Noise Measurements (min)
Available
Exctracted for SESAME
Earthquake Recordings
Weak Motion (velocity) - No Records
Weak Motion (acceleration) - No Records
Strong Motion (PGA >0.1g) - No Records
Magnitude Range
Distance Range (km)
Geological Data
Surface Geology(Rock-Stiff-Soft)
Stratigraphy & Lithology
Bedrock Depth (m)
Geotechnical - Geophysical Data
SPT-values
CPT-values
Vp (m/sec)
Vs (m/sec)
Q
r (gr/cm**3)
Basin Geometry
fo (hz)
Shape
Width (km)
Depth (km)
Length (km)
Closest Distance from Edge (km)
Surface Topography
Site Description
Ground Coupling
Information on Noise Measurements
No Records
Ref. Site
Remarks
Lefkas[LEF]
30
Continuous
30min
100
100
20
25
PRO
Y
10 to 15
Y up to 10m
N
Y up to 10m
Y up to 10m
N
Y up to 10m
Cross-Hole
0.3
Cylindrical
5
0.5
5
0.3
Flat
Page 19
Recorder Type
Sensor Type
Sampling Frequency
Gain
Data Format
Recording Period
Information on Earthquake Measurements
Recorder Type
Sensor Type
Sampling Frequency
Gain
Data Format
Recording Period
GPS
Contact Infornation [Institute/Person]
SESAME -ASCII
SESAME -ASCII
CETE/A-M. Duval
- Appendix C-2: Ambient noise data vs damage level
(Standard
Information
Sheet
for
each
experimental site) -
Information
Remarks
Site [Name/ Location]
Causative Earthquake
Date
Magnitude
Focal Mechanism(N-T-SS)
Coordinates
Depth (km)
Intensity Distribution
Discrete in Space
Equal-Damage Map
Intensity Scale
Other Type of Losses
Type of Constructions
RC
Masonry
Stone
Wooden
Noise Measurements
No of Sites
Existing
Planned (when?)
Recorder Types
Sensor Types
Sampling Frequencies
Gain(s)
Data Format
Recording Period
Earthquake Recordings
No of Sites
Weak Motion (<0.1g)
Strong Motion(>0.1g)
Recorder Types
Sensor Types
Sampling Frequencies
Gain(s)
Data Format
Recording Period
☺ Up to now, the time table is respected. The first stage of the WP including the gathering of already available
earthquake recordings and noise data, and the performing of experimental measurements and preliminary
processing of ambient vibrations at the strong motion sites and at selected sites of the cities affected by strong
earthquakes is going on. A first deliverable D04.04 “Homogeneous data set of noise and earthquake
recordings at many sites” will be produced for September2002.
Page 20
V
WP05 – T01.05: instrument layout for array measurements – year 1
Leader: Frank Scherbaum (Partner 3 – UPOTS.GEO – Postdam – Germany)
Within the context of this work package the dependence of the array performance (for phase velocity
determination) on the experimental conditions (array geometry, aperture, number of sensors, sensor types,
timing accuracy) shall be assessed.
The input needed for this task are:
−
existing array measurement data sets from within the consortium,
−
array measurements performed at well known test sites within the consortium,
−
relative calibration of instruments with respect to a broadband sensor (phase response),
−
computer codes for the calculation of the array transfer functions.
In a pilot study performed at the Institute of Geosciences, University of Potsdam (Streich and Scherbaum,
2001), the dependence of array geometry, array aperture, distribution of noise sources and the influence of
uncertainties of sensor phase responses on the phase velocity determination by standard f-k analysis (e.g.
Kvaerna and Ringdahl, 1986) have been investigated. For the evaluation of the array performance a set of
synthetic seismograms have been calculated by passing a broadband input signal through an allpass filter with
frequency dependent phase delays derived from the dispersion relation for a realistic site. Several conclusions
could be made from this work: within an intermediate frequency band all investigated array geometries give a
satisfactory result in terms of the derived dispersion curve. Phase response distortions of seismometers resulting
from up to 1% deviation in the calibration information have little influence for the apertures and station
distances considered.
However, besides natural limitations in the performance for higher frequencies due to spatial aliasing effects,
the performance for lower frequencies has not been satisfying. It has been shown, that for a dominating noise
source region (source-receiver azimuths not equal distributed), the dispersion curve could be recovered, whereas
for an azimuth random distribution, the derived apparent velocity values are highly overestimated. As possible
explanation for these findings it has been suggested that the superposition of array transfer functions for signals
arriving from different azimuths always lead to a bias in the slowness estimate.
Conclusions to be drawn are the following:
1. For f-k analysis of ambient noise in lower frequency bands it is necessary to preselect time windows which
contain a dominant surface wave train from a single azimuth for the analysis.
2. Test array methods providing higher resolution (e.g. Capon, 1969)
3. Test array methods using different assumptions about the observed wavefield, i.e. random wavefield (i.e.
spatial auto-correlation method SPAC, Aki, 1957).
These conclusions have lead to the selection of array analysis methods to be studied within WP06 (compare:
SESAME 2nd progress report, May 2002).
In order to test various array analysis methods within the given task, a new set of synthetic seismograms has
been calculated (compare SESAME 2nd progress report, WP06, May 2002). Furthermore, the SESAME partners
have decided on four main test sites within the consortium where field experiments will be conducted. Until
present, field data has been acquired for the main test site in Belgium by the Laboratoire de Géologie de
l’Ingénieur - Université de Liège - and the Observatoire Royal de Belgique - sub-contractor of SESAME project
and in the German-Switzerland border region close to Basle by the University of Postdam. The corresponding
field experiments for the remaining sites in Colfiorito (Italy) and Thessaloniki (Greece) will be conducted at the
end of July, beginning of August 2002.
☺ Up to now, the time table is respected. In November 2002, two deliverables, one on a tentative strategy for
array deployment and performance evaluation D06.05 “Array data set for different sites”, and a second on field
survey D07.05 “Optimum deployment strategy and quality measure for array layout in view of obtaining
surface wave” will be produced.
Page 21
VI
WP06 – T01.06: array measurements – derivation of dispersion curves – year 1
Leader: Frank Scherbaum (Partner 3 – UPOTS.GEO – Postdam – Germany)
Within the context of this work package a semi-automatic processing system for the array analysis of ambient
vibrations shall be developed. The array processing has the final objective to derive the dispersion curve
characteristics for the investigated site.
We have selected four standard array methods for the analysis of ambient vibrations. The four selected methods
differ both in the assumptions made for the analyzed wavefield as well as in the feasibility of the methodspecific experimental setup. Three of those four methods, the “slantstack analysis” (SL, e.g. Louie, 2000), the
“f-k analysis” (FK, e.g. Kvaerna and Ringdahl, 1986) and the “high-resolution f-k” (HRFK, Capon, 1969)
assume the arrival of coherent plane waves crossing the seismic array. Whereas for the SL method only a onedimensional array setup is required - thus one of the preferred methods in terms of logistical considerations both FK and CAPON need a two-dimensional array setup. The last method to be investigated is the spatial
autocorrelation method (SPAC, Aki, 1957). This method assumes a stationary random wavefield and provides a
theoretical relationship between the correlation of sensor pairs for differing azimuths and spatial distances and
the dispersion characteristics of surface waves. The logistical demand for the experimental setup of the array
configuration is high for the SPAC method. A dense semicircular array configuration with a large number of
sensors and very exact positioning is required, resulting in a severe drawback for the feasibility of this method
within the context of field campaigns in densely populated areas (cities). A modification of Aki’s SPAC has
been presented by Bettig et al. (2001) which relaxes the necessity for an exact deployment of a semicircular
array.
At Institute of Geosciences, University of Potsdam (IGUP) the algorithms mentioned above have been
implemented as a standalone C-program named „cap“. The field data is organized in a database (GIANT,
Rietbrock and Scherbaum, 1998) and checked interactively within the GIANT/ PITSA (Scherbaum and
Johnson, 1992) analysis environment for suitable time windows. Once the time windows are extracted, cap is
started to process this time window with a few command line options and method specific parameters given via
a configuration file. In Figure 1 a flow chart of the main processing steps in cap are shown.
Figure 1: Flow chart of main
processing steps in cap software
module. The uppermost block
describes the information retrieval
from the GIANT database system.
Besides the raw waveform data,
station
specific
information
(geographical
coordinates
and
instrument calibration) has to be
retrieved. The preprocessing block
performs at first a check for data gaps
and station dropouts. Then an offset
removal is applied to the total length
of the selected data. In order to make
the individual waveforms comparable
within the array, a simulation of a
common instrument response is
performed after Seidl (1980). The
optional
prefiltering
of
the
waveforms is implemented as a user
configurable Butterworth bandpass
filter. The last block shows
schematically the data processing in a
sliding window. The step width
between successive analysis windows
is dt, and the analysis is performed
over the whole trace length from
t=start to t=end.
query GIANT database
• retrieve waveform data
• retrieve station coordinates
• retrieve calibration information
preprocessing
• data consistency check:
check for data gaps, missing stations
• offset removal
• seismometer simulation (optional)
• bandpass filtering (optional)
init: t 1 = start, t 2 = start+winlen
apply selected method
(SL,FK, HRFK,SPAC)
in sliding window perform statistic and
derive dispersion curve
with error estimates
t 1 = t1 + dt
t 2 = t2 + dt
t 2 <end
NO
STOP
YES
process window [t 1 ,t2 ]
store t 1 , results
Page 22
As output cap provides the derived dispersion wave curve for the time window under consideration with
additional error estimates.
Currently under development is an automatic extraction of suitable time windows for processing. Furthermore
the database interface is to be ported to a free available SQL-database (i.e. mySQL, www.mysql.org). As
database structure we will use the CSS3.0 tables which is a standard in seismological applications (PIDC,
CTBT). Furthermore we intend to use not only vertical component data (as done so far), but also the
information of the horizontal components to check the data automatically for the assumption of arriving surface
waves (e.g. as suggested in Tokimatsu, 1997). Both Rayleigh and Love type waves shall be considered.
Other partners within the consortium have also implemented several array methods within their own processing
schemes (Table 1). During the software workshop held in Potsdam in January 2002, all partners agreed on the
interchange of source codes and the testing of the consortium partners’ software with both synthetic and real
data sets.
SESAME Partner
3 - University of Potsdam - UPOTS.GEO
1 - Université Joseph Fourier - UJFG.LGIT
6 - Polytechnic School of Zürich – ETH.GEOP
Array analysis algorithm
Slantstack
f-k
high-resolution f-k
modified SPAC (vertical component)
modified SPAC (3 components)
Beamforming f-k
high-resolution f-k
coding/platform
C / Linux, Solaris
Fortran / Solaris
Matlab signal processing toolbox / MS
Windows, Linux, Unix.
Table 1: Contribution of array analysis software within the SESAME consortium
In the current phase of the project, the algorithms are tested with both real data sets obtained from test sites and
synthetic noise data. For the real data sets used it has been a requirement that for the test sites under
consideration a number of geotechnical information is available in order to confirm the results of the dispersion
curve inversion.
Figure 2: a) 100 discrete
event locations (circles)
distributed
randomly
around
the
station
configuration in the center
(red
rectangle).
The
maximum source-receiver
distance for this synthetic
data is 10 km from the
center of the station
configuration.
The
azimuthal coverage of the
source location resembles
an equal distribution.
Page 23
The simulation of ambient noise from synthetic data has been achieved as follows: we have calculated a set of
100 discrete events with random azimuthal and distance distribution for a set of 222 receivers (Figure 2). The
source-receiver distance range for the discrete events has been restricted to lie between 0.1 km to 10 km. In all
cases the seismic source has been a vertical single force at the surface (radial symmetric radiation within 1Dvelocity model). The 1D-velocity models used resemble typical site conditions. Within the software meeting in
Potsdam, all partners involved in the array processing work package agreed on those site conditions where field
experiments have been or will be performed during this year (Liege, Grenoble, Thessaloniki). Thus a
comparison between real data sets and synthetic data sets is possible. For the calculation of the synthetic
seismograms for each source-receiver combination we have used a modal summation technique implemented by
R.B. Herrmann (Herrmann, 1987).
In order to simulate synthetic ambient noise, the single discrete events have been shifted randomly in time and
summed with different configurable weights (Figure 3). By applying this superposition principle a “controllable
ambient noise” situation can be achieved (i.e. non-random distribution of noise sources). A comparison of the
results obtained for the SL, FK and HRFK techniques for a single event and a circular array configuration is
shown in Figure 4.
(a)
(b)
Figure 3: a) Set of synthetic seismograms for discrete event. b) Synthetic simulation of ambient noise seismograms
obtained via superposition of weighted discrete events shifted randomly in time.
Figure 4: Comparison of array
analysis methods for synthetic
example for the source-receiver
configuration shown in the right
panel (upper: station geometry;
lower: source receiver geometry red circles show the radial wave
propagation from point source
location). The color coded map
shows the result for the slantstack
analysis from low (violet) to high
(red)
beampower
values
displayed in the frequencyapparent velocity plane (1dimensional wavenumber along
event-receiver
line).
Superimposed is the theoretical
dispersion curve for an arbitrary
velocity model. White bars with
black diamond symbol indicate the results obtained for the f-k algorithm (bar width indicates the frequency band of
analysis, diamond the center frequency). The white dots in the upper half of the f-v plane show the results of the high
resolution f-k algorithm for each discrete frequency. Dots are reflected to the upper half plane for display reasons only. A
good agreement of the dispersion curve results is found for all algorithms within the frequency band from 0.1 to 3 Hz.
Page 24
☺
Up to now, the time table is respected. In November 2002, one deliverable D05.06 “Quality control
software for in-situ checks” will be produced. This software will be designed so that it can be used on a small
workstation or a PC during field experiments as well as for post-processing.
VII WP07 – T01.07: array measurements – inversion of velocity profile – year 1
Leader: Denis Jongmans (Partner 4 – ULGG.DGO – Liège – Belgium)
The aim of this WP is to extract the S (Vs) and P (Vp) wave velocity profiles from the dispersion curve
calculated by the WP06. Usually, Herrmann’s codes (Hermann, 2001) are used to perform this inversion but
some strong limitations led us to look for another way of converging towards the solution(s).
At the beginning of this WP, we made a literature review to consider all possible options about the inversion
scheme: linear methods, Monte-Carlo, Simulated Annealing, Genetic and Neighbourhood. The last three
methods appeared to be a good compromise between the time consumption and the solving of the problem.
In order to implement these methods, it is important to have a quick and robust algorithm to solve the direct
problem, i.e. the calculation of the dispersion curve of a theoretical geological model. A C++ program, mainly
inspired by the Herrmann’s code, has been developed during this year. It presents some slight differences in the
way the curve are calculated to overcome the lacks of the former code. Very good performances compared to
the Herrmann’s code were observed during the first tests. Intensive runs were performed to correct all bugs; the
actual version is stable and ready for the next stage of the development.
Until now, only the Neighbourhood algorithm has been used on very simple synthetics models (a soft sediments
layer over a hard bed rock) with promising results for the inversion of Vs and Vp. Further tests have to be done
in the next weeks to extend it to more sophisticated geological configurations where the non-uniqueness of the
solution will appear.
The a-priori information is very important and can help discriminating among all models that equally comply
with the measured dispersion curve. We are looking for a rational way of including it in the inversion process.
Real data sets are necessary to test the performances of all possible approaches. This is why we conducted a
series of array measurements with the collaboration of Matthias Orhnberger and Frank Scherbaum in Liège and
Uccle (Belgium, March 2002). Many interesting a-priori information are available for both sites: PSV and SH
refraction profiles, surface wave’s measurements with artificial sources, boreholes with geological description
are well distributed over the area and various Cone Penetration Tests are available. The analysis process has just
started.
The main items developed during the first year are detailed below.
1. Inversion method: Neighbourhood Algorithm
This method, developed by M. Sambridge in 1999, searches a zone within the parameter space for the minima
of the cost function. The dimension of the space is normally limited to 30 or 40. For more degrees of freedom
the program loose efficiency and does not converge easily to the solution. It does not calculate any derivative of
the cost function. The computation is divided into several iterations (parameter “Itmax”). Each iteration adds
“ns” new models to the global set according to the results calculated so far. The newly generated models are
randomly chosen over the “nr” most promising areas of the parameter space. The Voronoy geometry is used to
map the cost function in the parameter space. The “nr” areas are the Voronoy cells where the cost function is
minimum. “ns”, “nr” and “itmax” are the only tuning parameters of the method. This is a great advantage
compared to the Genetic algorithm and the Simulated Annealing. As “nr” increases, more areas are explored and
the algorithm behaves more as a sampler with slower convergence. Voronoy cells have a very interesting
property: if the convergence is trapped in a local minimum, there are good chances to get out of it as new
models are generated.
The final result of the method is not only the best model parameters but also an estimation of the density of
probability around this solution. It is also possible to investigate the non-uniqueness of the solution as the final
Page 25
set of models can contain various items with the same value for the cost function. Statistical analysis of the
resulting set of model is used to quantify the information provided by the ambient vibration measurements
(uncertainties and resolution). The a-priori knowledge may be merged with the dispersion curve information to
reduce the uncertainties.
2. Direct Problem or forward calculation: C++ developments
First tests on a simple model show that a wrong calculation of the dispersion curve (e.g. mode jumping) can
drastically slow down the convergence. This is why a new robust algorithm has been studied.
For Love and Rayleigh waves, the problem consists of finding the couples (frequency, wave number) where a
certain determinant vanishes. It is a function of model parameters calculated using the Thomson-Haskell method
or the propagator matrix method. The Herrmann’s implementation was simply translated from Fortran77 to
C++.
The forward calculation adopted here differs from the Herrmann’s one in the way the roots are searched.
Herrmann’s code always constructs the dispersion curve from the higher frequency where all modes tend to
merge (except the fundamental in the Rayleigh case) causing mode jumping if the search step for roots is too
large. Lower values for this step increase CPU time needed.
Thus, before calculating the curve at the desired sample points (frequency or period), we construct a stair
function that separates each mode from the next one. As in Herrmann’s code, we need to define a search step.
Mode jumping occurs when the step is too high. However, it automatically produces oscillations in the
dispersion curve that are detected before sending the results to Neighbourhood algorithm. The stair function
construction accepts all “special” shapes of the dispersion curve that arise when the ratio Vp/Vs is high or when
the contrast between the half space and the superficial layers is weak. Finally, the roots can be found without
any confusion of mode.
To speedup the forward calculations, automatic adjustment of the parameters of the stair function construction
are still under study.
3. Inversion of a basic model using components of §1 and §2
We started testing the Neighbourhood algorithm with the forward calculation described here above. A basic
RMS function was taken as the cost function. The design of the program allows any other choice without great
modification.
The theoretical dispersion curve was calculated using our algorithm and Herrmann’s code on the following
model (results are identical):
Soft Layer
Hard layer
Thickness
H1=50 m
infinite
Vp
Vp1=500 m/s
Vp2=2000 m/s
Vs
Vs1=250 m/s
Vs2=1000 m/s
Density
2
2.5
Then, from the calculated curve, we tried to find back Vp1, Vs1, Vs2 and H using inversion. Good recovery was
achieved (1 or 2% error depending on the parameter).
The parameters must be rescaled to fit in a parameter space with fixed boundaries: every parameter can vary
between two fixed values. But Vs2 must be greater than Vs1 and the Poisson’s coefficient for the first layer
must be consistent. Vp2 is calculated with a fixed Poisson’s coefficient. Those conditions generate a parameter
space with irregular boundaries.
The influence of the parameterization will be analysed in the next year, especially for models with a greater
number of layers.
☺ Up to now, the time table is respected. During the first year test of existing methods on synthetic 1D models
and development of an effective and reliable inversion technique allowing a priori information has been done.
During the next year, the work will focus on processing and inversion of the dispersion curve obtained during
experiments and in May 2003, a first deliverable D14.07 “Report on the inversion of velocity profile and
Version 0 on the inversion software” will be produced.
Page 26
VIII WP08 – T01.08: nature of noise wavefield – year 1
Leader: Pierre-Yves Bard (Partner 1 – UJF.LGIT – Grenoble – France)
The first year has been basically devoted to a literature survey, in order to determine the main research
directions for the following. This work has been achieved mainly within LGIT Grenoble by Sylvette BonnefoyClaudet, a PhD student funded by the SESAME project, under the scientific supervision of Pierre-Yves Bard
and Fabrice Cotton. This section will thus summarize the main aspects of this literature survey, as well as its
conclusions regarding the nature of noise wavefield, and the work to be done in the next year.
1. General overview
Microtremors have been observed early during the nineteenth century. In 1872, Bertelli installed a pendulum
and observed during many years that sometimes the pendulum moved continuously for hours or days. He
noticed a correlation between the “microseisms” and disturbed air pressure (Gutenberg 1958). Since this date
many studies about microtremor have been carried out. We can distinguish three predominant time periods.
Until the middle of the twentieth century, studies were more qualitative than quantitative: progress in
knowledge was limited by instrumental techniques. However, some authors highlighted important
characteristics of microtremor. Relations between microseisms, meteorological conditions and oceanic waves
have been pointed out by Banerji (Banerji 1924-1925). He observed in south Asia, microseisms associated with
Indian Monsoon, and suggested that they are due to Rayleigh waves set up at the bottom of the sea by the train
of water waves maintained by the monsoon currents.
In 1958, Gutenberg (Gutenberg 1958) quoted a bibliography containing 600 references about microseisms.
Unfortunately, the major part of these references are in foreign language (German, Italian …) and they were
published in local scientist journal. It is difficult to obtain microtremor references until the 50’s.
During the 50-70’s, improvements in instrumental technique allowed lots of noise survey. In order to understand
noise wavefield composition, several techniques have been used: particule motion (Toksoz 1964), arrays
techniques led to F-K analysis (Capon et al., 1967; Capon, 1969 Lacoss et al., 1969) and SPAC analysis (Aki
1957), boreholes techniques coupling with arrays analysis (Douze 1964-1967, Gupta 1965). The vast majority of
works on noise wavefield composition has been done in this time period. Different conclusion about origin
(oceanic, meteorological, human …) and nature (P waves, surfaces waves) of microtremor have been drawn. It
is detailed in the following section "Nature of noise wavefield".
From the 80’s up to now, the number of microtremor publications increase every year. Since it is not always
easy to list these publications (especially Japanese publications), we can just estimate the number of
microtremor publications: about 500. Some of them are devoted to the nature of noise wavefield, but an
overwhelming majority (about 95%) is dealing with the applicability of microtremor, and/or their direct
applications to some specific case studies.
The most important application is the microzonation in the cities. There are two major techniques: site to
reference spectral ratios, and H/V ratio. The second method is largely using than the first one. The H/V ratio
technique was proposed first by Nogoshi in 1971, and then strongly emphasized by Nakamura (Nakamura
1989). Since this date, many authors have published a lots of papers about microzonation using H/V ratio (see
Bard, 1999 for a review). Although few authors (Lachet and Bard 1994, Kudo 1995) attempted to find
qualitative explanations about Nakamura’s technique, the major part of the authors assume that basements of the
method are right.
An other application of noise background vibration is array technique to obtain velocity profile. Studies started
in the late 50's, but improvements in computer, and instrumental techniques (3-components seismometer,
numeric data), in the last 3 decades, allow an increase in quantity and quality of data recording during array
surveys (Malagnini et al. 1993; Matshushima and Okada 1996, Miyakoshi and Okada 1996; Chouet et al., 1998;
Liu et al. 2000; Kudo et al. 2002; Bettig et al. 2002).
Unfortunately, in these studies authors assume that nature and origin of microtremor are (well) known, and do
not care about this issue. It is usual to read in paper « we assume that microtremor consisting in surface waves »,
and no more explanation !
Page 27
2. Nature of noise wavefield
As mentioned in the previous section, most of the knowledge about microtremor was obtained during the 6070’s.
Most authors seem to agree about the origin of microtremor. There conclusions may be summarized as follows:
− at long periods (T>2s) microtremor are due to large scale oceanic meteorological conditions;
− at intermediate periods (1<T<2s) they are mainly generated by effect of wind and local meteorological
conditions;
− at short periods (T<1s) they are linked to human activities.
The distinction between long period (T>1s) and short period (T<1s) noise corresponds to the traditional
distinction between « microseisms » with natural origin, and « microtremor » with an artificial origin. However,
the 1s border line between these two domains may be shifted to longer periods, as shown by Seo (Seo 1997): in
urban areas characterized by low frequency, high impedance-contrast subsoils , artificial microtremor may be
more energetic than natural microseisms even at intermediate periods (up to a few second). An easy way to
distinguish microseisms from microtremor is the significant daily amplitude variations (with a factor of 3 to 4
between day and night) of the microtremor.
Concerning the composition of noise wavefield, this literature survey does not allow to conclude to a unique,
unambiguous solution. It is usually admitted and demonstrated that microseisms (natural origin) consist mainly
in fundamental Rayleigh waves (which may, however, include a few higher modes) (Longuet-Higgins 1950,). It
is more difficult to define the nature of microtremor (T<1s): some authors conclude that urban noise consist of P
waves (Gupta 1965, Li 1984), while other conclude in surface waves (Toksoz 1964, Douze 1964, Horike 1985,
Liu 2000), and sometimes a mixed of them (Li 1984). Moreover, when noise wavefield consist in surface
waves, authors do not agree on whether Rayleigh waves (fundamental and/or higher modes) or Love waves, are
predominant
A major conclusion of this literature survey is therefore that authors do not draw the same conclusions about
composition of noise wavefield! More work must thus be done, in order to quantify several proportions
concerning the nature of microtremor:
− surface waves / body waves,
− rayleigh waves / love waves,
− fundamental (rayleigh) mode / higher modes.
Some author attempted to give partial responses at these questions. Chouet (Chouet et al. 1998) analysed the
volcanic tremor wavefield on the Stromboli volcano (SPAC arrays method). He found very significant
proportion of surface waves in the total noise power, and amongst them, about 30% of Rayleigh waves and 70%
of Love waves. More recently, Cornou (2002) has analysed noise wavefield in the basin of Grenoble (France)
with MUSIC arrays analysis, she finds a proportion of 60% of Rayleigh waves and 40% of Love waves. One
must be aware, however, these measurements are not homogeneous as they not always represent the same
quantities.
These first quantitative results have been obtained, in all cases, through array measurements. Therefore, our
work in the next year will be essentially relying on a detailed analysis of the array data obtained in various sites
(Grenoble, Volvi, Colfiorito, Basel, Liège, and Nice) within the SESAME consortium, and on the comparative
analysis of synthetic noise simulations performed on those sites and on a number of canonical models as well.
☺
Up to now, the time table is respected. The first year has been basically devoted to a literature survey, in
order to determine the main research directions for the following and to data gathering. During the next year, the
work will focus on the analysis of array data available within the consortium. A deliverable D13.08 “Report on
the nature of noise” will be produced for May 2003.
Page 28
IX
WP09 – T01.09: numerical simulation of noise – year 1
Leader: Peter Moczo (Partner 11 – IGSAS.SD – Bratislava – Slovakia)
This WP focuses on the development and validation of numerical models producing realistic noise synthetics. It
mainly uses Finite-Difference technique (FD) with spatially and temporally random surface sources, and include
parameter studies to investigate the ability of H/V and array techniques, applied on synthetics, to recover the
information on he structure.
During this first year, the Fortran95 Program Package NOISE for numerical generation and simulation of
seismic noise in 3D heterogeneous viscoelastic media has been developed. This package is much more powerful
than the tool that has been used for preliminary tests in WP06, since it accounts for lateral structure variations.
The program package consists of two programs: program RANSOURCE and program FDSIM. The flowchart of
the Program Package NOISE can be found in the report of the first deliverable D02.09 “FD code to generate
noise synthetics”.
Program RANSOURCE is designed for random space-time generation of point sources of seismic noise. The
output files serve as input files for the program FDSIM.
The algorithm of random noise generation assumes regular spatial distribution of potential point sources inside
of a specified source volume. The spatial distribution is controlled by the prescribed minimum distance between
two neighbour point sources, minimum distance between a point source and a receiver, and maximum distance
between a point source and a receiver.
The temporal distribution of point sources is controlled by the prescribed minimum and maximum numbers of
point sources acting at the same time.
For each generated position of a point source, a direction of acting single body force at the position, time
function and maximum amplitude are randomly generated.
The time function is either delta-like signal or pseudo-monochromatic signal (a harmonic carrier with the
Gaussian envelope). Spectrum of the delta-like signal is low-pass filtered in order to fit the prescribed frequency
range. In the case of the pseudo-monochromatic signal, first its duration, then its predominant frequency are
randomly generated.
The maximum amplitude of the signal is randomly generated from the interval (0,1> according to a chosen
distribution.
The program has to be run before the finite-difference simulation of the noise itself. The program generates two
files for all delta-like sources and as many files as the number of generated pseudo-monochromatic sources. All
the files serve as the input data files for the program FDSIM.
Program FDSIM is designed for the finite-difference simulation of seismic wave propagation and seismic
ground motion in a 3D surface heterogeneous viscoelastic structure with a planar free surface.
The computational algorithm is based on the explicit heterogeneous finite-difference scheme solving equations
of motion in the heterogeneous viscoelastic medium with material discontinuities. The scheme is 4th-order
accurate in space and 2nd-order accurate in time. The displacement-velocity-stress scheme is constructed on a
staggered finite-difference grid.
The computational region is represented by a volume of a parallelepiped with the top side representing a planar
free surface, and bottom, rear, front, left and right sides representing either non-reflecting boundaries or planes
of symmetry. Different types of non-reflecting boundaries can be chosen on different sides of the computational
region.
The discontinuous spatial grid is used to cover the computational region. The upper part of the grid has three
times smaller grid spacing than the lower part. Each part itself is a uniform rectangular grid.
The rheology of the medium corresponds to the generalised Maxwell body. This makes possible to account both
for spatially varying quality factors of the P and S waves and for arbitrary Q-omega law.
The wavefield is excited by a set of randomly generated point sources, each representing a single force acting in
an arbitrary direction.
The core memory optimisation is applied in order to significantly reduce requirements of the computer’s core
memory.
Page 29
A set of canonical models for seismic noise simulations has been defined. The set consists of the following
models (each being described in detail in the first deliverable D02.09 “FD code to generate noise synthetics”):
•
•
M1 : homogeneous halfspace,
M2 : single layer over halfspace
`
`
`
•
•
•
•
M3 : dipping layer, semiinfinite layer over halfspace,
M4 : semi-infinite layer over halfspace,
M5 : single layer with a rough layer-halfspace interface,
M6 : deep sediment valley
`
`
•
A – 2D case
B – 3D, axisimmetric case
M9 : buried fault
M10 : two-layer models
`
`
•
A – 2D case
M8 : single layer with a trough at the bottom
`
`
•
•
A – 2D case
M7 : shallow sediment valley
`
`
•
parameter study with several mechanical parameters
single layer over halfspace – Grenoble,
single layer over halfspace – Liege,
A – thick and shallow layers
B – two shallow layers, with and without velocity inversion
M11 : shallow layer, gradient model
`
`
A – with increasing velocity
B – with decreasing velocity
The set of canonical models will serve for extensive parametric study of synthetic seismic noise which will
create a basis for deducing systematic features of the noise and decisive factors determining peak H/V and HT
(VT) frequencies and corresponding amplitudes.
This list is, however, subject to changes after the first computations with the NOISE program: the main unknown concerns
the computer time. If it proves to be too heavy for the resources available within the consortium, then only part of this
"ideal" set will be considered.
Several methods of time-frequency analysis, including traditional windowed Fourier transform, Wigner
distribution, continuous and discrete wavelet transform, wavelet packets, windowed Fourier transform with the
reassignment method, continuous wavelet transform with the reassignment, and the matching pursuit
decomposition with the redundant Gabor dictionary, were implemented and numerically compared. The
properties of the above methods were compared for a set of simple canonical synthetic test signals and for a
complicated non-stationary synthetic signal with a known time-frequency content. Though the Wigner
distribution has many excellent properties, due to cross-terms it is not good for TFA of complicated multicomponent signals. The windowed Fourier transform is not suitable due to the fixed window width. Suitable
methods are, e.g., the continuous wavelet transform and its combination with the reassignment. The
reassignment method can improve localisation properties and readability of the time-frequency representation.
A very promising method is the matching pursuit decomposition with the Gabor dictionary. An improvement of
the matching pursuit decomposition has been developed. With the extended Gabor dictionary the method is
capable to correctly represent a linear dispersion in an analysed signal.
☺
Up to now, the time table is respected. The first year has been devoted to the development of computation
method(s), and computer codes for 3D modelling of seismic-noise wavefield for realistic models of sourcestructure configurations. A first deliverable D02.09 “FD code to generate noise synthetics” in the form of a
CD ROM with a report describing the flow chart of the software and canonical structural models has been
produced and presenting with this first year progress report. The next step will be to perform numerical
simulations for the selected set of canonical models. A next deliverable D12.09 “Report on parameter studies”
is foreseen for May 2003.
Page 30
X
References
Aki, K., 1957. Space and time spectra of stationary stochastic waves with special reference to microtremors, Bull. Earthq.
Res. Inst., 35, 415-456.
Banerji, S.K., 1924-1925. Microseisms associated with SW monsoon, Nature, 114:576, 116:866.
Bard, P.-Y., 1999. Microtremor measurements: a tool for site effect estimation ?, State-of-the-art paper, Second
International Symposium on the Effects of Surface Geology on seismic motion, Yokohama, December 1-3, 1998, Irikura,
Kudo, Okada & Sasatani, (eds), Balkema 1999, 3, 1251-1279.
Bettig, B., P.-Y. Bard, F. Scherbaum, J. Riepl, F. Cotton, C. Cornou and D. Hatzfeld, 2001. Analysis of dense array
noise measurements using the modified SPatial Auto-Correlation method (SPAC) . Applicatio to the Grenoble area.
Invited paper, Boletin de Geofisica Teorica e Applicata, in press.
Capon, J., 1969. High-Resolution Frequency-Wavenumber Spectrum Analysis, Proceedings of the IEEE, Vol. 57, No. 8,
pp.1408-1419.
Capon, J., R.J. Greenfield and R.J. Kolker, 1967. Multidimensional maximum-likelihood processing of a large-aperture
seismic array, Proc. IEEE, 55, 192-211.
Chouet, B., G. De Luca, G. Milana, P. Dawson, M. Martini and R. Scarpa, 1998. Shallow velocity structure of
Stromboli Volcano, Italy, derived from small-aperture array measurements of strombolian tremor, Bull. seism. Soc. Am.,
88-3, 653-666.
Cornou, C., 2002 : Traitement d’antenne et imagerie sismique dans l’agglomération grenobloise : implications pour le
risque sismique, Thèse de doctorat de l’Université Joseph Fourier, Grenoble-I.
Cornou, C., P.-Y. Bard, M. Dietrich, 2002. Contribution of dense array analysis to basin-edge-induced waves
identification and quantification. Methodology (I), submitted to BSSA.
Cornou, C., P.-Y. Bard, M. Dietrich, 2002. Contribution of dense array analysis to basin-edge-induced waves
identification and quantification. Application to Grenoble basin, French Alps (II), submitted to BSSA.
Douze, E. J., 1964. Rayleigh waves in short-period seismic noise, Bull. seism. Soc. Am., 54-4, 1197-1212.
Douze, E. J., 1967. Short-period seismic noise, Bull. seism. Soc. Am., 57-1, 55-81.
Gupta, I.N., 1965. Standing-wave phenomena in short-period seismic noise, Geophysics, 30-6, 1179-1186.
Gutenberg, B. 1958. Advances in geophysics, Vol.5, p. 53, Academic press, New-York.
Herrmann, R.B., 1987. Computer programs in Seismology, Volume IV, Department of Earth & Atmospheric Sciences,
Saint Louis University.
Herrmann, R.B., 2001. Computer programs in seismology: an overview of synthetic seismogram computation, Version
3.1,
08/03/2001,
Department
of
Earth
and
Atmospheric
Sciences,
St-Louis
University.
http://www.eas.slu.edu/People/RBHerrmann/ComputerPrograms.html
Horike, M. 1996. Geophysical exploration using microtremor measurements. In: Eleventh World Conference on
Earthquake Engineering, CD-ROM, Paper n° 2033, Acapulco, Mexico, Elsevier Science Ltd.
Horike, M., 1985. Inversion of phase velocity of long-period microtremors to the S-wave velocity structure down to the
basement in urbanized areas, Journal of Physics of the Earth, 38, 59-96.
Kudo, K., 1995. Practical estimates of site response, State-of-the-Art report, Proceedings of the Fifth International
Conference on Seismic Zonation, Nice, October 1995.
Kudo, K., T. Kanno, H. Okada, O. Özel, M. Erdik, T. Sasatani, S. Higashi, M. Takahashi, and K. Yoshida, 2002.
Site specific issues for strong ground motions during the Kocaeli, Turkey, earthquake of August 17, 1999, as inferred
from array observations of microtremors and aftershocks, Bull. seism. Soc. Am., 92-1, in press.
Kværna, T., and Ringdahl, F., 1986. Stability of various f-k estimation techniques, in: Semiannual Technical Summary, 1
October 1985 - 31 March 1986, NORSAR Scientific Report, 1-86/87, Kjeller, Norway, pp. 29-40, 1986.
Lachet, C., and P.-Y. Bard, 1994. Numerical and theoretical investigations on the possibilities and limitations of the
"Nakamura's" technique, Journal of Physics of the Earth, 42, 377-397.
Lacoss, R.T., E.J. Kelly M.N. Toksöz, 1969. Estimation of seismic noise using arrays. Geophysics, 34-1, 21-38.
Li, T.M.C., J.F. Ferguson, E. Herrin & H.B. Durham, 1984. High-frequency seismic noise at Lajitas, Texas, Bull. seism.
Soc. Am., 74-5, 2015-2033.
Liu,H.-P., D.M. Boore, W.B. Joyner, D.H. Oppenheimer, R.E. Warrick, W. Zhang, J.C. Hamilton & L.T. Brown,
2000. Comparison of phase velocities from array measurements or Rayleigh waves associated with microtremors and
results calculated from borehole shear-wave velocities, Bull. seism. Soc. Am., 90-3, 666-678.
Longuet-Higgins, M.S., 1950. A theory on the origin of microseisms, Philos.Trans. R. Soc. Lond., A243: 1-35.
Page 31
Louie, J.N., 2001. Faster, Better: shear-Wave Velocity to 100 Meters Depth From Refraction Microtremor Arrays, Bull.
Seism. Soc. Am., Vol. 91, No. 2, pp. 347-364.
Malagnini, L., A. Rovelli, S.E. Hough and L. Seeber, 1993. Site amplification estimates in the Garigliano valley, central
Italy, based on dense array measurements of ambient noise, Bull. seism. Soc. Am., 83, 1744-1744.
Matshushima, T. and H. Okada, 1990. Determination of deep geological structures under urban areas using long-period
microtremors. BUTSURI-TANSA, 43-1, 21−33.
Miyakoshi, K., and H. Okada, 1996. Estimation of the site-response in the Kushiro City, Hokkaido, Japan, using
microtremors with seismometer arrays, Xth World Conf. Earthq. Engng., Acapulco, # 900, Elsevier Science Ltd.
Nakamura, Y, 1996. Real-time information systems for seismic hazard mitigation UrEDAS, HERAS and PIC, Q.R. of
RTRI, 37-3, 112- 127.
Nakamura, Y., 1989. A method for dynamic characteristics estimation of subsurface using microtremor on the ground
surface. QR of R.T.R., 30-1 .
Nakamura, Y., 1996. Real-time information systems for hazards mitigation, Xth World Conf. Earthq. Engng., Acapulco, #
2134, Elsevier Science Ltd.
Nogoshi, M. and T. Igarashi, 1971. On the amplitude characteristics of microtremor (Part 2), Jour. seism. Soc. Japan, 24,
26-40 (in Japanese with English abstract)
Rietbrock, A. and Scherbaum, F., 1998. The GIANT analysis system, Seismological Research Letters, Vol. 69, No. 6,
pp. 40-45.
Sambridge, M, 1999. "Geophysical inversion with a neighbourhood algorithm: I. Searching a parameter space", 1999,
Geophysical Journal International, Vol 138, pp 479-494.
Scherbaum, F. and Johnson, J., 1992. PITSA, Programmable Interactive Toolbox for Seismological Analysis, IASPEI
Software Library, Vol. 5.
Seo, K., 1997. Comparison of measured microtremors with damage distribution, JICA Research and Development project
on Earthquake Disaster prevention , 306-320.
Seo, K., 1997. Cooperative observation of microtremors in Kobé-Hanshin district, Japanese document, in Japanese with
English abstract, 38-46
Streich, R., and Scherbaum, F., 2001. Optimierung der Anordnung seismischer Mikro-Arrays für Bodenunruhemessungen, 61. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, Frankfurt.
Tokimatsu, K., 1997. Geotechnical site characterization using surface waves, in: Earthquake Geotechnical Engineering,
Ishihara (ed.), pp. 1333-1368, Balkema, Rotterdam.
Toksöz, M.N., 1964. Microseisms and an attempted application to exploration. Geophysics, 29-2, 154-177.
Page 32
SESAME synopsis
As outlined in the sections describing each active work package, the project is progressing normally, according
to the schedule, and there does not exist any major problem that jeopardize the chance of success of this project.
I will therefore only emphasize the major achievements of this first year, after stating some general comments.
I
Co-ordination
1. General atmosphere
First of all, my overall feeling is that the general atmosphere of the project has been very good, cooperative and
enthusiastic from the very beginning. The sharing of responsibilities between the coordinator, task leaders, and
WP leaders, has been working smoothly and efficiently. The workpackage and task leaders have organized their
WP and established work plans clearly assigning responsibilities and roles of every involved partner. All
participants – scientists and technicians - from the 14 partner teams did perform very efficiently their assigned
work according to the schedule, with extensive exchanges with other participants through electronic mails and
work meetings. As a consequence of that good atmosphere, this project involves many individuals (more than
60 during the first year, see the participant list), who, obviously, are only part time on the project.
Of course, in such a large group, the ideas and viewpoints are never unanimous; but up to now, when decisions
had to be made involving large groups, it was done after extensive exchanges of viewpoints and arguments, and
decisions have been made on a compromise / consensual basis rather than on an authoritarian basis. The
coordinator feels very much concerned that such a situation will continue till the end of the project.
The very good organizational work performed by our "assistant manager" Laurence Bourjot allows everybody
to focus on the scientific and technical part of the work.
2. Test sites
In order to check thoroughly the two techniques that are concerned in this project (H/V and array), it was
decided during the first general meeting to apply them to a number of well-known sites, where detailed
geotechnical and geophysical information is already available.
These test-sites were selected from the experience and background of some consortium teams. They are five:
• Volvi (Greece): the European test site is one of the best known in Europe, thanks to two previous projects
where two SESAME partners have been involved (EUROSEISTEST, EUROSEISMOD). It is relatively
deep and soft (h = 200 m, f0 = 0.7 Hz, 2D site)
• Grenoble (France) : this very thick, relatively stiff site (h > 500 m, f0 = 0.3 Hz, 3D site) has been
thoroughly studied by the Grenoble team in recent years because of observed very large, broad band
amplifications. It is typical of large alpine valleys.
• Colfiorito (Italy) : this site has been extensively studied by the Italian partner after the Umbria-Marche
sequence of 1997-1998, because of spectacular 2D/3D amplifications and ringing . It is a good example
of many small alluvial basins in the Appenine and in "intermediate mountain" areas. It is however, rather
deep, and low frequency (h > 100 m, f0 = 1 Hz).
• Basel (Switzerland) : this important urban and industrial area is, alike the Grenoble area, the object of
extensive investigations by the Zurich partner. It is also a rather thick site (h > 200 m, f0 < 1 Hz).
• Liège (Belgium) : this is the only shallow site (h < 20 m, f0 = 5 Hz), and it is typical of many urban sites
with thin alluvial / fluvial deposits.
Page 33
In addition, some attention will be paid also to two other sites:
• Uccle (near Brussels, site of the Royal observatory),
• Nice (another urban area, typical of many coastal cities along the Mediterranean Sea).
3. Coordination tools
•
A project logo has been chosen through a vote during the Potsdam meeting from several proposals. The
propositions were from inside the consortium, in order to save money. This logo is extensively used in
this progress report, on the web site, and in all the deliverables.
•
A web site has been set up (http://SESAME-FP5.obs.ujf-grenoble.fr) and is maintained by the Grenoble
group (coordinator), on which are posted a description of the project, the minutes of the various
meetings, the deliverables, and a number of intermediate work documents.
•
Despite an extensive use of electronic mails, "physical" meetings are still irreplaceable: the number of
general meetings has been willingly limited to 3 throughout the whole duration of the project, but there
have been, during this first year, a rather large number of work meetings (Bergen, Zurich, Potsdam,
Milano, Grenoble, Nice): this has induced a significant amount of travel costs, although all participants
tried their best to limit them at the lowest possible level (group travels by car, over week-end stays, …).
4. Administrative information
•
Partner 1 - UJF: nothing to declare
•
Partner CR2 - Résonnace: Corinne Lacave being on maternity leave from May 2002 to November 2002,
Martin Koller will be during this time the scientific in charge of the work done in the project. For this
reason, he is the only one who have signed the first year cost statement.
•
Partner CR3 – UP: The chancellor of the University of Postdam changes the 18 October 2001. Mr
Alfred Klein was replaced by Mrs Steffi Kirchner, who signed the first year cost statement.
•
Partner CR4 – ULGG: The cost statement has been signed by the Financial Manageress of the
University of Liège, Anne Girin, and not by the Rector Willy Legros.
•
Partner CR5 – UiB: nothing to declare.
•
Partner CR6 – ETH: nothing to declare.
•
Partner CR7 – ITSAK: The cost statement has been signed by the Financial Officer Panagiota
Papadimitriou and not by the President of the Board of Directors Basil Papazachos.
•
Partner CR8 – ICTE/UL: nothing to declare.
•
Partner CR9 – INGV: nothing to declare.
•
Partner AC10.9 – CNR-CSGAQ/IDPA The Milano partner has changed its status: it remains a CNR
institute, but is has been joined with another CNR center based in Venezia, and its name has thus
changed from "Centro di Studio per le Geodinamica Alpina e Quaternaria (CSGAQ)" to "Istituto per la
Dinamica dei Processi Ambientali (IDPA)". A copy of the corresponding decree by the CNR President
is enclosed (Appendix p. 41).
•
Partner CR11 – GPISAS: nothing to declare.
•
Partner AC12.1 –CETE.Nice: nothing to declare.
•
Partner CR14 – LCPC: nothing to declare.
Page 34
II
Scientific and technical achievements
1. Task A
Although far from its end, Task A has already provided significant results. The instrumental results described in
Deliverable D01.02 very clearly assess the performance of the various sensors and their limitations (see Table 9
in D01.02), and allow to recommend some and to advise against some others; similar results have also been
reached for data acquisition systems (see Tables 7 and 8 in D01.02). We will have to be careful for the
publication of those results, since some manufacturers (well ranked) already asked for these reports, very
probably in order to take a commercial advantage from our results. We plan to send an individual letter to each
of the various manufacturers, with a copy of the deliverable, before submitting a synthesis paper for publication.
The ongoing series of tests about the field experimental protocol have also already yielded somewhat surprising
results on soil/sensor coupling conditions. They bear an outmost importance for the practical implementation of
the method: they will be therefore crosschecked carefully before being reported in the next deliverable from
Task A (D04.02).
The development of the H/V software was designed in view of optimizing its portability and simplicity for field
or lab uses in developed AND developing countries. This led the consortium to take difficult decisions, - after
an internal, passionate but democratic debate - , regarding a) the possible extension of the software for other
more sophisticated uses, and b) the default data formats to be built-in the software. In both cases, the final
decisions were made by attributing a heavy weight to the final goal of designing a simple tool for routine use by
non-specialists all over the world.
Finally, for the empirical assessment of the H/V technique (WP04), the ongoing gathering of all data already
existing within the various teams of the consortium (Greece, Italy, France, Switzerland, Portugal) will allow to
build up a very large data set, which will in turn allow to derive very meaningful statistical results.
2. Task B
This task has faced some early difficulties linked with the physical move of the Liège responsible scientist to
another place (another laboratory of the Grenoble University), and the resulting resign of the other Liège
scientist who was initially scheduled to work on the project. These difficulties could, however, be solved after
some months, with the appointment of a new PhD student (M. Wathelet), whose thesis is done under the cosupervision of Liège and Grenoble universities.
No deliverable is due at the end of the first year, so results are only preliminary. The optimization of the
instrumental layout will derive from a series of theoretical tests (already performed), and from the lessons from
the ongoing measurements on the various test sites decided within the consortium. Field measurements have
already been performed in Liège, Grenoble and Basel (+ another series in Nice); for the two remaining sites
(Colfiorito and Volvi), the measurements are scheduled for late July / early August.
The various array analysis techniques already developed in different teams of the consortium have been listed
(f-k, high resolution, SPAC); they all focus on the derivation of the dispersion curve for the fundamental
Rayleigh mode. The corresponding computer codes given to the Task leader, who is organizing them in a single
package for a thorough comparison. The requirements for this "array software" are very different from those on
the H/V software: the simplicity of use is not so important, since the techniques are rather sophisticated and
cannot be operated by non-specialists. The tests will be performed on both real data (from the well-known test
sites), and on synthetics from well-controlled models.
Finally, the inversion of the velocity profile is being approached with a new inversion algorithm, that allows to
take into account in a simple way some other information than the sole dispersion curve. Preliminary tests are
encouraging but much work remains to be done, as scheduled.
The discussions during the first general meeting outlined a new opportunity which had not been considered in
the initial workplan: after an idea from the Zurich partner (Fäh et al., 2002), it seems possible also to get
additional and strong constraints on the velocity profile directly from the H/V curve (provided this latter one is
Page 35
derived in a special way to be representative of the elliptic curve of Rayleigh waves). It has thus been decided to
include some work on this technique within Task B and not within Task A.
3. Task C
The main outcome of this task for the first year is the deliverable D02.09 “FD code to generate noise
synthetics”, consisting in a program package to generate noise synthetics for arbitrary 3D media. This program
is now being installed on three sites (Bratislava, Zurich and Grenoble) in order to share the very heavy
computational work corresponding to a set of canonical models (as also detailed in deliverable D02.09). This set
of canonical models, agreed upon in the Zürich meetings, comprises reference 1D models, 2D and 3D models. It
will serve for extensive parametric study of synthetic seismic noise which will create a basis for deducing
systematic features of the noise.
The literature review accomplished during this first year confirmed the fact that little has been learnt in recent
years about the actual composition of noise wave field. Moreover, different conclusions are reached by different
authors! Very little is known as to the proportions between surface and body waves, between Rayleigh and Love
waves, between fundamental and higher modes; and actually no robust, well accepted method presently exists
that can directly lead to these ratios. The only systematic fact is that all the (few) existing quantitative results
have been obtained through array measurements. Therefore, our work in the next year will be essentially relying
on a detailed analysis of the array data obtained in the various test sites (Grenoble, Volvi, Colfiorito, Basel,
Liège, Uccle and Nice) within the SESAME consortium, and on the comparative analysis of synthetic noise
simulations performed on those sites and on a number of canonical models as well.
III
Dissemination of results
This is the basic aim of Task D, scheduled to start after the end of the second year. However, a number of
presentations have already been done in several conferences (see the list in the appendix), one paper has been
published, another one has been submitted.
Kristek, K., P. Moczo, and R. Archuleta, 2002. Efficient methods to simulate planar free surface in the 3D 4th
–order staggered-grid finite-difference schemes. Stud.. geophys. geod., 46, 2002, 355-381.
Fäh, D., F. Kind and D. Giardini, 2002. Inversion of local S-wave velocity structures from average H/V
ratios, and their use for the estimation of site effects. submitted to Journal of Seismology, January
2002.
Other conferences are planned to advertise the project results (amongst which a key-note lecture during the next
meeting of the European Seismological Commission – Genoa, September 2002 - will be partially devoted to the
SESAME project).
Also, the time and location of the scientific workshop scheduled for the beginning of the third year have been
decided: it will take place in the Smolenice Castle in Slovakia on September 21-23, 2003. This facility, owned
and operated by the Slovak Academy of Sciences, offers very cheap accommodation; it cannot, however, host
more than 80 participants. We will therefore have very soon to decide our policy for the opening of this
workshop to "non-SESAME" scientists, considering that
a) we do not have within the project the financial resources to invite foreign visitors;
b) as outlined before, there already exist a large number of scientists participating in the project from
within the consortium
c) our initial will was to have in the attendance both a few renown scientists from all over the world,
and "potential users" from developing countries.
The final decision on the attendance policy will be taken during the next general meeting in Rome.
Page 36
SESAME important dates
1
2
3
4
Months
May 2001
June 2001
July 2001
Aug. 2001
5
6
Sept. 2001
Oct. 2001
7
8
9
Nov. 2001
Dec. 2001
Jan. 2002
10
11
12
Feb. 2002
March 2002
April 2002
13
May 2002
14
15
16
17
18
June 2002
June 2002
July 2002
Aug. 2002
Sept 2002
Oct. 2002
19
20
21
22
23
24
Nov. 2002
Dec. 2002
Jan. 2003
Feb. 2003
March 2003
April 2003
25
May 2003
26
27
28
29
June 2003
July 2003
Aug. 2003
Sept. 2003
30
31
32
33
34
35
36
Oct. 2003
Nov. 2003
Dec. 2003
Jan. 2004
Feb. 2004
March 2004
April 2004
37
38
May 2004
June 2004
Week 1
Week 2
Week 3
Week 4
Kick-off Meeting-Grenoble
Zürich – Aug 29-30
Task C meeting
Bergen – Oct 22-26
Instrument workshop
TaskA - WP02
Postdam – Jan 7-8
Instrument workshop
Preparation of report
TaskA-WP02
First progress report
(AGU)
Postdam – Jan 9-11
Software & Array processing
techniques
TaskA-WP03 & TaskB-WP06
During the EGS – Nice – April 21-27
Ap 21-22:Instrument workshop Finalisation of report
Ap 23-24: WP02 Experimental conditions
Ap 25: WP04 Data compilation
Ap 26-27: WP03 Software development
Task A- WP02- WP 03- WP 04
D1, D2
Zürich
Task C meeting
Second report: first yearprogress report
D3: Progress report 1
(due on 30/06/02)
D4
(ECEE London)
Roma – Oct 23-26
Oct 22 : WP09-10 meeting
Oct 23: WP04 Empirical evaluation
Oct 24: WP03 Software development
Oct. 25-26: General SESAME meeting
D5, D6, D7, D8
(AGU)
D9
EGS – Nice
D11, D12, D13,D14, D15
(due on 30/06/03)
D16, D17, D18, D19
Bratislava – Sept 22-24
Scientific Workshop
D20,D21
(AGU)
EGS – Nice
General Meeting - Nice
D22, D23, D24
D25; Final report
Page 37
SESAME annexes
I
Minutes of the meetings or workshops
The minutes of the different meetings or workshops are available on the web site:
http://SESAME-FP5.obs.ujf-grenoble.fr
II
Presentations to International conferences
1.Communication to the AGU in San Francisco (USA), 10-14 December 2001
VIBRATIONS ON THE ROLL-MANA, A ROLL ALONG ARRAY EXPERIMENT TO MAP LOCAL SITE EFFECTS
ACROSS A FAULT SYSTEM
M. Ohrnberger,(1), F. Scherbaum (1), K.-G. Hinzen (2), S.-K. Reamer (2), B. Weber (2)
(1)
Institut für Geowissenschaften, Universität Postdam, POB 601553, Potsdam, Germany, [email protected].
(2)
Abt. für
Erdbebengeologie des Instituts für Geologie der Universität zu Köln, Vinzens-Palotti-Str.26, Bergisch-Gladbach, 51429
Germany.
The effects of surficial geology on seismic notion (site effects) are considered one of the major controlling factors to the
damage distribution during earthquakes. Qualitative and quantitative estimates of local site amplifications provide
important information for the identification of potential high risk areas. In this context, the analysis of ambient vibrations is
an attractive tool for the mapping of site conditions. It is low-cost alternative to expensive active seismic experiments or
geophysical well-logging and especially well suited for the use within urban areas.
Within the MANA experiment we conducted ambient vibration measurements at roughly 100 sites in the Lower Rhine
Embayement (NW-Germany) to test various aspects of site effect determination, especially the feasibility of a roll along
technique. A total of 13 three-component seismometers (5s corner period) have been used in a linear array configuration
(station distance ~ 100 m). At all times during the roll-along experiment at least 8 stations (mostly 10) were operating
simultaneously, meanwhile the other stations were moved from the rear to the front of the line and re-installed. Thus, a total
progress of almost 10 km could be obtained within two days. The line stretched across the NW-SE striking Erft fault
system, one of the major faults in the eastern part of the Lower Rhine Embayement.
The thickness of cenozoic soft-sediments overlying the basement of paleozoic age increase at the individual branches of the
fault in abrupt steps of uncertain magnitude from around 200 m in the east to almost 100 M in the west.
The results of single station horizontal to vertical spectral ratios (HVSR) along the line are presented as well as the spatial
evolution of local dispersion curves obtained from a slantstack analysis (SSA). The spatial variation of feature along the
line in both the HVSR and SSA are discussed in terms of sedimentary thickness and modifications of the wavefield
properties of the ambient vibrations.
The following page is a presentation of the complete poster.
Page 38
Mettre le poster de Matthias (1 page de fichier pdf)
Page 39
2. Communication to the 3a Assemblea Hispano-Portuguesa de Geodesia y
Geofisica, Valencia, Spain, 4-8 Feb 2002
TESTS FOR THE INTERPRETATION OF SEISMIC INTENSITIES ANOMALIES AT THE AZORES: MICROTREMOR SURVEY ON
POVOAÇÃO COUNTY (S. MIGUEL ISLAND)
Ensaios para a interpretação de anomalias de intensidades sísmicas nos Açores: estudos de ruído ambiental no Concelho da
Povoação (ilha de S. Miguel)
Paula Teves-Costa(1), C. Riedel(2,3), J.L. Gaspar(2), D. Vales(4), G. Queiroz(2), M.L. Senos(4,5), N. Wallenstein(2), F. M. Sousa(5) e M.
Escuer(5)
(1)
Centro de Geofísica da Universidade de Lisboa e Departamento de Física da Faculdade de Ciências da Universidade de
Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa, Portugal, [email protected]. (2) Centro de Vulcanologia e Avaliação
de Riscos Geológicos, Universidade dos Açores, 9501 801 – Ponta Delgada. (3) Instituto de Geofísica, Universidade de
Kiel, Alemanha. (4) Instituto de Meteorologia, Rua C do Aeroporto, 1700 Lisboa, Lisboa. (5) Instituto de Meteorologia,
Delegação Regional dos Açores, Ponta Delgada.
Presentation done in Spanish with a summary in English.
The seismic activity of the Azores Islands is known since the beginning of their settlement in the middle of the XV century.
About 30 earthquakes produced social and economical important damages. The analysis of the damage distribution, for
several earthquakes, shows systematically the existence of site effects. In order to understand the initial cause of these
effects, we selected three different zones, with different geological and geomorphological characteristics, in the Povoação
County, and we performed a microtremor survey. Pseudo-transfer functions for each site, H/V, were calculated according
to the Nakamura methodology. The interpretation of the dominant frequencies must take into consideration not only the
geological characteristics, but also the structural geomorphology.
3. Communication to the EGS, Nice, France, 22-26 Apr. 2002
INFLUENCE OF INSTRUMENTS ON H/V SPECTRA OF AMBIENT NOISE
B. Guillier (1), K. Atakan (2), A-M. Duval (3), M. Ohrnberger (4), R. Azzara (5), F. Cara (5), J. Havskov (2), G. Alguacil (6), P. TevesCosta (7), Nikos Theodulidis (8) and the SESAME Project WP02-Team.
(1) LGIT, Observatoire de Grenoble, BP 53 – 38041 Grenoble Cedex - France, [email protected] (2) UiB, Bergen, Norway,
(3) CETE, Nice, France, (4) IGUP, Potsdam, Germany, (5) INGV, Rome, Italy, (6) UG, Granada, Spain, (7) CGUL, Lisbon, Portugal, (8)
ITSAK, Thessaloniki, Greece.
Microtremor measurements are commonly used in microzonation studies for hazard assessment and engineering purposes.
In this respect a very widely used methodology in recent years is the computation of H/V spectral ratio of ambient
excitations. SESAME project aims to investigate the reliability of this technique, both from the experimental and
theoretical point of view. The first step is to check the stability and reproducibility of the measurements. Before testing the
experimental conditions that may influence the H/V ratio, a workshop was devoted to perform a set of tests in order to
compare the performance of different equipments currently used (13 digitizers and 15 sensors). All data collected for
instrument tests were converted into a common format and processed using a common software for homogeneity. The first
set of tests was devoted to analyse the physical properties of the digitizers (internal noise, time stability, sensitivity, channel
consistency) and the minimum noise value able to be recorded for different gains and with different sensors. The second set
of tests was dedicated to the sensor analysis. We check the performance of each sensor connected to the same digitizer. The
last set of tests consisted of simultaneous measurements of noise by all the systems (digitizer-sensor combinations),
performed on a concrete pier coupled directly with the bedrock in the laboratory, as well as outside in the free-field, in two
different ground coupling conditions (grass and concrete). The preliminary results indicate that significant differences may
occur between the different systems, depending upon the digitizer-sensor combinations. In general, the digitizer tests
showed consistency with the manufacturers specifications. However, the combination with different sensors yielded
variable results, indicating the importance of the system performance as a whole and the level of sensitivity required for the
type of data collected. The sensor tests revealed the importance of the sensitivity required by the input ambient excitations
at frequency levels down to 0.1 Hz. Broad-band sensors gave higher resolution at lower frequencies, but they are difficult
to implement in a microtremor experiment, due to stability and portability problems. In general, sensors with 1-5 sec period
are more suitable for microtremor measurements. The H/V spectral ratios performed on the simultaneous measurements,
showed clear limitations on some of the sensor-digitizer combinations.
Page 40
MICROTREMOR SURVEY ON POVOAÇÃO COUNTY (S. MIGUEL ISLAND, AZORES): DATA ANALYSIS
AND INTERPRETATION
P. Teves-Costa (1), C. Riedel (2,3), D. Vales (4), N. Wallenstein (2), A. Borges (1,5), M.L. Senos (4), J.L. Gaspar (2), G. Queiroz (2)
(1) Centro de Geofísica da Universidade de Lisboa e DF-FCUL, Campo Grande, Edifício C8, 1749-016 Lisboa, Portugal,
[email protected], (2) Centro de Vulcanologia e Avaliação de Riscos Geológicos, Universidade dos Açores, Ponta Delgada, Portugal, (3)
Institut für Geowissenschaften, Kiel, Germany, (4) Instituto de Meteorologia, Lisboa, Portugal, (5) Instituto de Ciências da Terra e do
Espaço, Lisboa, Portugal.
The seismic activity of the Azores Islands is known since the beginning of their settlement in the middle of the XV century.
About 30 earthquakes produced social and economical important damages. The analysis of the damage distribution, for
several earthquakes, shows systematically the existence of site effects. In order to understand the initial cause of these
effects, three different zones were selected, with different geological and geomorphological characteristics, in the Povoação
County, to perform a microtremor survey. Seismic data were recorded on a grid of 50 m in the three regions, using a 3component Lennartz 1 Hz seismometer, with a sampling rate of 8 ms. The stations were deployed for 5 minutes or more to
record microtremor imposed on the topmost layers by natural and anthropogenic sources. The data were processed using
two different subroutine packages, in order to estimate the H/V ratio, defined according to the Nakamura methodology.
However, the two processing routines gave different results, which forced us to revise all the procedures and to identify the
main factors that caused it. Three portable seismic stations were installed in three fixed points, for about three months,
aiming to record some earthquakes. Several small magnitude earthquakes (m < 3.0) were recorded and these data were
processed in the same way as the noise data, obtaining reference H/V ratios. The interpretation of the dominant frequencies,
for noise and small magnitude earthquakes, was performed taking into consideration not only the geological characteristics,
but also the structural geomorphology.
III
Papers
Kristek, K., P. Moczo, and R. Archuleta, 2002. Efficient methods to simulate planar free surface in the 3D 4th –
order staggered-grid finite-difference schemes. Stud.. geophys. geod., 46, 2002, 355-381.
Fäh, D., F. Kind and D. Giardini, 2002. Inversion of local S-wave velocity structures from average H/V ratios,
and their use for the estimation of site effects. submitted to Journal of Seismology, January 2002.
IV
Deliverables
F D01.02 “Controlled instrumental specifications”: a report of 34 pages + 5 appendices. The complete
report will be available on a CD ROM. At this moment, it is on the anonymous ftp site of the University of
Bergen at the following address: ftp://ftp.ifjf.uib.no/pub/sesame/REPORT/FINALREPORT
F D02.09 “FD code to generate noise synthetics”: in the form of a CD ROM with a report describing the
flow chart of the software and canonical structural models.
F D03.01 “First year progress report”: the following report with the cost statements.
V
Other
F Copy of the decree signed by the CNR President (Partner AC10.9 – CNR-CSGAQ/IDPA)
Page 41

Second progress report: year 1

Transcription

Similar documents

Puppet- Master: leslie Carrara- rudolph

Sesame Street China

Kung Hei Fat Choi!

View - Prince George Digitization

Early Childhood Education by MOOC: Lessons from Sesame Street

Yakiniku

Chicken Lo Mein - Printable Kosher Recipes

Production - Sesame Workshop

theBoom "O"

KIDsiderate Guide