Assessing Volcanic and Seismic Activities and Hazard

Assessing Volcanic and Seismic Activities
and Hazard Mapping in the Philippines
Renato U. Solidum, Jr.
Philippine Institute of Volcanology and Seismology
Department of Science and Technology
Major natural hazards in the Philippines
Outline of Presentation
• Hazards and geotectonic setting of the
Philippines
• Monitoring volcanic and seismic activities and
hazard mapping
• Multi-hazard mapping initiatives
Tectonic Setting of the Philippines
The geographic and
geologic setting of
the Philippines make
it prone to various
hazards, including:
•typhoon/floods
•landslides
•volcano-related
•earthquake-related
•tsunami
INACTIVE VOLCANO
ACTIVEVOLCANO
EARTHQUAKE EPICENTER
1
Subduction Systems and Major Active Faults
in the Philippines
Seismicity of the
Philippines
(1608-2002)
Active Faults _____
Trenches
_____
Magnitude 4 or greater
~ at least 20
earthquakes recorded
per day
_____
~100-150 felt per year
~90 destructive
earthquakes for past
400 years
~ 40 tsunamis for past
400 years
Data sources:
NEIC for recent earthquakes (1897-2002)
Bautista and Oike for historical earthquakes (1608-1896)
Active, Inactive and
Potentially Active
Volcanoes of the
Philippines
Philippine Institute of Volcanology and Seismology
(PHIVOLCS) - Department of Science and Technology
• 300 volcanoes
• 22 considered active
(with recorded
eruption
or latest eruption
<10000 years)
• 27 potentially active
Responsible for monitoring, warning, hazards assessment
of, and (together with other organizations and local
governments) in implementing programs to minimize risks
from earthquakes, volcanic eruptions and tsunamis
2
Volcano Monitoring Networks
Example Volcano (Hibok-Hibok) Alert Level Signals
ALERT LEVEL
•
6 volcano observatories, with
several monitoring parameters
Seismic
Geochemical
Hydrological
Ground deformation
Visual observations
Pinatubo
Taal
Mayon
Bulusan
•
Quick Response Team and
mobile sets of monitoring
equipment for rapid deployment
No Alert
INTERPRETATION
No eruption in foreseeable future
1
Low level seismic, fumarolic,other unrest
Magmatic, tectonic or
hydrothermal disturbance; no
eruption imminent
2
Low to moderate level of seismic, other
unrest with positive evidence for
involvement of magma
Probable magmatic intrusion;
could eventually lead to an
eruption
3
Relatively high and increasing unrest,
including numerous b-type earthqukes,
accelerating ground deformation and
rockfalls, increased vigor of fumaroles, gas
emission
Increasing likelihood of an
eruption, possibly within days to
week
4
Intense unrest, including harmonic tremor
and/or many “long period” (=low frequency)
earthquakes or quiet lava emissions and/or
dome growth and/or small explosions
Magma close to or at earth’s
surface. Hazardous explosive
eruption likely, possble within
hours to days
5
Hazardous explosive eruption in progress,
with pyroclastic flows, surges and/or
eruption column rising at least 6 km or
20,000 feet above sea level
Explosive eruption in progress.
Hazards in valleys
and downwind.
Kanlaon
Hibok-hibok
Volcanic Hazards
CRITERIA
Background, quiet
Volcanic Hazards Assessment and Mapping
• Based on geological and historical products
and events, geomorphic/topographic
controls, numerical modeling
Pyroclastic flow
Ashfall
• Maps/assessment for short term prediction
(evacuation procedure before and during an
eruptive period) and for medium to longterm (land use and development planning)
• Identification of Permanent Danger Zones
(prohibition of settlement) in active
volcanoes
Lahar
(Volcanic mudflow/debris flow)
• Re-assessment (especially for short term
prediction) necessary during and after
major volcanic activities
Lava flow
HAZARD MAPPING
3
Extreme rainfall events on volcanic areas:
a concern especially with climate change
Extreme Rainfall Effect
Mayon Volcano, 2006 Lahar and Flashfloods
Mayon Volcano, 2006 Lahar and Flashfloods (~460 mm in 12 hours)
B
A
Upper reach
Middle reach
From delos Reyes et al, 2007 (PHIVOLCS-DOST)
A. Erosion of 10-20 meters along the upper reach and about 2 meter deposition and
subsequent 10 meter erosion along the middle reach of Masarawag Channel.
B. Two to four meter lahar deposition in a village.
Lahar Hazards Map
PHIVOLCS-DOST
Data Source: PHIVOLCS Field Data
SPOT 5, June 2006 (NAMRIA), ALOS (JAXA)
Earthquake Monitoring
• 64 seismic stations
- 29 unmanned stations
with VSAT
communication
-35 manned stations
From delos Reyes et al, 2007 (PHIVOLCS-DOST)
Development of Local Tsunami Warning System
(Deployment of Tsunami Sensors)
5m
Wet
Sensors
10 m
1
m
Dry Sensor
4
Seismic Hazard and Risk Assessment Software
Regional Scale Seismic Hazard Maps
•REDAS (Rapid Earthquake Damage
Assessment System) is a seismic
hazard simulation software that aims to
produce hazard and risk maps
immediately after the occurrence of a
strong and potentially damaging
earthquake or a scenario earthquake
Active Faults
(ground rupture)
•Developed by PHIVOLCS in 20022004 with seismic hazard maps and
earthquake data base
Liquefaction
Landslide
Tsunami
Hazards Mapping and Assessment for Effective
Community-Based Disaster Risk Management
(READY PROJECT)
• A four-year project (2006-2010)
• Multi-hazard, multi-agency, communitybased strategy
• Managed under the National Disaster
Coordinating Council with technical
government organizations implementing the
project together with local governments and
communities
• With United Nations Development
Programme (UNDP) as the implementing
agency of donors (ex. UN, AusAID)
•Currently being shared with local
government disaster managers and
planners
READY Project
• The project will cover 27 provinces and has three
(3) main components:
1. Multi-hazard identification and disaster risk assessment
(1:50,000 to 1:10,000 for floods, rain-triggered landslide, storm
surge, ground shaking, ground rupture, earthquake-triggered
landslide, tsunami)
2. Community-based disaster preparedness
Information, Education and Communication
Community based Early Warning Systems
3. Initiate the mainstreaming of risk reduction into the
local development planning process
5
Thank you!
www.phivolcs.dost.gov.ph
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