Seismic Hazards, Pakistan - NCEG

Seismic Hazards, Pakistan:
A Review
M. Asif Khan
National Centre of Excellence in Geology
University of Peshawar
• Seismology basics!
• Seismic Hazard Zones, Pakistan
• Principal Seismic Sources (Faults),
Pakistan
• Seismic Hazard Analysis: Methodology
• Seismic Hazard Map of Pakistan and its
interpretation
• Shortcomings & Future Strategies
SEISMOLOGY BASICS!
"An earthquake is the way
the Earth relieves its
stress by transferring it to
the people who live on it."
on a door at Santa Monica College
Courstesy Dr. Lucy Jones at USGS at California Institute of Technology
“Shifting masses of rocks
miles below the Earth’s
surface cause the
earthquakes and the waves
of energy that they make”
John Michell, 1760
Strike Slip
Where do the
Earthquakes
occur?
Role of
Plate
Boundaries
in
generating
/localizing
Frequency of Occurrence
Shaking Duration
1220 km
Magnitude & its Effects?
Fault Rupture
Worldwide 1995
1000
Kilometers
Seconds
100
10
1
110 km
100
10
1
5.5
6
6.5
7
Magnitude
7.5
8
5.5
6
6.5
7
Magnitude
7.5
8
Site:
Ground motion Vibration (Intensity)
(Acceleration, velocity, displacement)
Epicentre
Epicentral
Isoseims Distance (R)
Surface
Site
Depth
Propagation
Path
Hypocentre
Hypocentre:
Earthquake Magnitude
Hypocentral Distance (r)
Wave Propagation Path:
Energy Loss & geometrical spreading
Shear Waves_S Waves
Compression Waves_P Waves
Wave Type
Velocity
(km/sec)
Rayleigh
3-4 km/sec
love
3.5-4.5 km/sec
S
5-7 km/sec
P
8-11 km/sec
SEISMOTECTONICS
PAKISTAN
ChamanHindukush
KirtharSulaiman
Makran
KuchchBhuj
Hazara-Potwar
Himalayas
Kashmir Himalayas
cum
Indus-Kohistan
H
Kashmir 2005,
M7.6
Kangra 1905, M
~8
Kashmir Earthquake 2005:
Quetta 1935,
Himalayan
Seismic Zone
M7.5 Consequences & Causes
ChamanHindukush
Seismic Zone
Muchh 1931,
Himalayan
M. Asif
Khan
M7.4
Seismic
Zone
National Centre of Excellence in
Geology
Sulaiman-Kirthar
University of Peshawar
Seismic Zone
Armora 1945,
M8.3
Makran Seismic Zone
Kuchch-Gujerat
Seismic Zone
Bhuj 2001 M7.6;
Allah Band 1819
M 7.8
Surface damage in the
Thar-Nagar Parker Region,
SE Sindh, Pakistan
Bhuj January 26, 2001
Earthquake:
Kirthar
Fold-Belt
Thar Desert
Indus Basin
Karachii
Kuchch Mainland Fault
Nagar
Parker
Asian
Plate
Indian Plate
33 mm/yr
Ormara
15±5 mm/yr
triple
junction
4
Karachi
3±2 mm/yr
Kachchh
Tectonic Map of the Himalayas
Khaltoro
Valley
Khaltoro
Valley
Brittle FaultsBrittle Faults
Sassi
Sassi
Shahbatot
Shahbatot
Mylonite
Mylonite
S
Hurban Fault trace
Dasu-Sassi Fault Trace
Indus
Dasu Gorge
Sassi
Khaltoro Gorge
Vertical
Mylonites
Flat lying
Kohistan marbles and
amphibolites
1
2
Kamila
Amphibolite
intruded by
pegmatite dyke
network
Mylonite Zone
Brittle Fault Gouge
Zone
Brittle Fault 1
Ujnal Nala
Mylonite Zone
Kinematic features,
suggesting E-side up
diplacement
Bunji
Gorge
Brittle Fault 1
Indus
Vertical
brittle
faults
ASTOR R.
RAMGHAT R.
MMT
RAIKOT F.
3
2
1
4
BRITTLE FAULTS WITH
GOUGES
New Astor
Bridge
INDUS R.
Raikot-Liacher Thrust
Kohistan
Diorite
Brittle
Faults
MMT
Kamila Amphibolite
Nanga Parbat
Metasediments
A
Glacial
Till
Amphiboli
te
Gouge
Zone
B)
4
N
3
2
1
Liachar
Thrust
5
Indus
W
E
Tectonic Map of the Himalayas
SALT RANGE
Kalabagh Fault
VELOCITY FIELD
POTOWAR PLATEAU, N. PAKISTAN
• GPS Measurements 2003 & 2006
• Velocities relative to Chiniot,
Kiriana Hills
• Green line-Uniform Slip Elastic
Model
• Velocities
•North of MBT, 8±1 mm/yr
•Potwar Plateau 2-4 mm/yr
•Punjab Plains 2 mm/yr
Greco & Spencer, 1993
Bossart et al., 1988
Kashmir Block
o
45 Clockwise
Rotation
Bossart, Ottiger &
Heller, 1990
2005
Treloar et al., 1990
-30km
-1m
-4m
Chi-Chi Earthquake, Taiwan 1999, 7.5 Mw
Shih-Kang Dam
Nisar Camp, Muzafarabad
Neelam River
5m
Water Channel
Water Channel
SEISMIC HAZARD ANALYSIS
SEISMIC HAZARD ANALYSIS
Seismic hazard vs. risk
Seismic risk = seismic hazard * exposure
* vulnerability * cost
Seismic Hazard – The probability of
experiencing a specific ground shaking
at a specific site or region due to
earthquakes.
Seismic Risk Analysis
• Macro seismic hazard analysis
– Deterministic seismic hazard analysis
(DSHA)
– Probabilistic seismic hazard analysis
(PSHA)
• Micro seismic hazard analysis
– Soft ground effects analysis
– Liquefaction analysis
• Vulnerability and risk analysis
– Building vulnerability, vulnerability curves
– RADIUS, HAZUS approach
Difference!
• Deterministic seismic hazard analysis (DSHA)
– Use a single scenario
“The earthquake hazard for a site is a
– Select a single magnitude, Mpeak ground acceleration of 0.35g
from an earthquake of
– Select a single distance, R resulting
magnitude 6.0 on a Specific Fault at a
– Assume effects due to M, R distance of 12 km from the site. ”
• Probabilistic seismic hazard analysis (PSHA)
– Assumes many scenarios
– Consider all magnitudes
– Consider all distances
– Consider all effects
“The earthquake hazard for
the site is a peak ground
acceleration of 0.28g with a
2 percent probability of
being exceeded in a 50-year
period.”
Seismic Hazard Maps
of Pakistan and
their interpretation
Tirich Mir-Misgar F.
Fault Map of
Pakistan
MKT
Indus-Kohistan F
Muzafarabad T.
Kurram T.
MMT
Panjal T.
SRT
MBT
Waziristan T.
Chaman F.
Kalabagh F.
Jhelum F.
Sulaiman Frontal T.
Ghazaband T.
Hoshab F.
Kirthar F.
Hoshab F.
Pab F.
Rann of Kuchh F.
MakranSubduction Zone
OrnachNal F.
After NESPAK 2006
Raisi T.
Seismo-Tectonic Map, Pakistan
After NESPAK 2006