Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Probabilistic Seismic Ground Motion Hazard Analysis: A Tool for Disaster Risk Management
Henremagne C. PEÑARUBIA
Philippine Institute of Volcanology and Seismology (PHIVOLCS)Department of Science and Technology (DOST), Philippines
OBJECTIVE:
To enhance the engineers’ and disaster managers’
understanding of the potential ground motion hazard
in the region for consideration in the seismic design,
risk assessment and disaster risk management.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Why Engineers should
be concerned?
Deaths caused by
collapsing structures?
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
• A fault is a break, fracture, fissure or zone of weakness where
movement or displacement had occurred or may occur again. It may
extend hundreds of kilometers across the earth’s surface and tens of
kilometers downward.
• An active fault is a fault that has moved within the last 10,000 years. It
shows evidence or has documented history of its movement.
• A trench is the deepest portion on the sea floor. It is a manifestation of a
subduction zone where a tectonic plate moved or is pushed under by
another tectonic plate.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
• Earthquake is a weak to violent shaking of the ground produced by the sudden
movement of rock materials below the earth’s surface. It usually occurs along
tectonic plate boundaries and active faults.
• Ground shaking could be felt in the
vertical and horizontal direction
coupled with circulatory and
oscillatory motion.
• Magnitude may be between 1<Mw >9.5
• Hypocenter varies from 1<depth>800km
http://www.iris.edu
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Seismic Hazards observed
in the Philippines
Earthquake HazardsSeminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
PHIVOLCS websitehttps://www.phivolcs.dost.gov.ph
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Ground Rupture Hazard Maps - Regional
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Provincial Hazard Maps
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Fault Finderhttp://www.faultfinder.phivolcs.dost.gov.ph
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Liquefaction Hazard Map
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
• An earthquake can also cause soil materials on a slope to become unstable by the imposed inertial load causing loss of strength in the slope. These landslides and rock falls may be observed on hillsides and mountainous regions experiencing ground shaking intensity greater than PEIS V.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Earthquake-induced Landslide Hazard Map
Tsunami Hazard Map
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Earthquake Information Page
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Ground Shaking Hazard
• The shaking of the ground caused by the faulting and propagation of released energy
in the form of perceptibly mild to intense vibration at the passage of the seismic waves on
site. The wave train is essentially composed of body waves and surface waves.
• 1. Body waves are either the compressional (push or up) or extensional motion (pull or
down), also called primary wave, or the shear motion (sway or side to side), also called
secondary wave, usually felt as intense shaking but of short duration.
• 2. Surface waves, on the other hand are oscillatory motions orthogonal to the secondary
wave and circulatory motions opposite to the direction of the primary wave. These are
usually less intense felt undulations but relatively of longer duration.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
The characteristic of earthquake ground motion which have the greatest impact to houses and structures are:1. duration2. amplitude (displacement, velocity and acceleration)3. frequency of the ground motion
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Deterministic Hazard Maps and Tool
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
•On the right-hand side of PHIVOLCS’ frontpage
are the links to the recently-launched atlases onprobabilistic seismic hazard Analysis (PSHA).
•The PSHA of the Philippines and Metro Manila, also known as the Philippine Earthquake Model
(PEM) Atlasprovides: peak ground acceleration (PGA) maps
on rock site at 10%, 5% and 2% PoE in 50 years.
It also provides:
spectral acceleration (SA) maps at 0.2 sec, 0.5 sec, 0.8 sec, 1.0 sec and
3.0 sec natural periods at 10% PoE in 50 years on stiff soil for the
whole archipelago.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Probabilistic Hazard Maps
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
National Structural Code of the Philippines (NSCP 2015)
Source: NSCP 2015
F = ma V = 2.5CaIW/R
The more intense the acceleration (g) is,
the larger the force acting on the structure!
Base shear
Figure 208-3, Design Response Spectra
Risk = hazard * exposure * vulnerabilty
avoidance proper construction
Risk Management
reductionminimize control measures
Recommendations• Enhance the engineers, community planners and disaster
managers’ understanding of earthquake hazards, exposure,
and vulnerability of structures and communities.
• Update and strictly implement the seismic design
requirement of the National Structural Code of the
Philippines.
• Invest in building resilient structures and communities.
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University
Your knowledge and course of action may save lives, resources and livelihood!
http://www.phivolcs.dost.gov.ph
http://www.faultfinder.phivolcs.dost.gov.ph
http://gisweb.phivolcs.dost.gov.ph
https://hazardhunter.georisk.gov.ph
Seminar on Earthquake Engineering and Disaster Risk Management22 August 2019, Romblon State University