Download VII. Earthquake Mitigation

VII. Earthquake Mitigation
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B.
C.
D.
E.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake “forecasting” (prediction)
Engineering and Building Codes
Preparation in earthquake prone areas
VII. Earthquake Mitigation
A.
Approach to earthquake mitigation
Main approach is survivability
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Requires hazard identification and risk assessment
Identify areas of where materials at risk of seismic
wave amplification and enhanced ground shaking
risk
Engineering solutions to make structures
earthquake resistant
Preparation and training of emergency response
teams and medical personel
Earthquake prediction and evacuation is not a
reasonable goal in the foreseeable future
VII. Earthquake Mitigation
A.
B.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Hazard Identification: deals primarily with the science
○ defining and describing a hazard, its physical characteristics,
magnitude and severity, probability and frequency, causative
factors, and locations or areas affected
Risk Assessment: deals with the societal impact issues
○ Estimating vulnerability of and impact on populations,
probabilities of events and magnitude, frequency and return
period, mitigation planning
VII. Earthquake Mitigation
Hazard Identification and Risk Assessment
Shaking Hazard map = statistical probability (10% chance in 50 year period)
exceeding a stated level of shaking (as % of g = acceleration of gravity)
Need to know…
Probability of a future
EQ of given magnitude
(need to understand
past behavior and how
faults work)
Response of materials
to shaking (intensity)
(need to understand
how shaking varies
with materials and how
materials vary with
geographic location)
VII. Earthquake Mitigation
A.
B.
C.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake “forecasting” (prediction)
Long-term forecasting (probabilities of future fault slip)
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Based on past behavior
Historical records + pre-historical records + fault mapping = total record
VII. Earthquake Mitigation
A.
B.
C.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake prediction
Long-term forecasting (probabilities of future fault slip)
Historical Records
• written and verbal accounts (100s of years)
• measured seismic activity (~100 years of data)
• distribution of earthquake activity on a both a
global and local scale
Data for U.S.
Earthquakes
VII. Earthquake Mitigation
C. Earthquake prediction
Long-term forecasting (probabilities of future fault slip)
Fault mapping
• Understanding the distribution of faults and
linkage of faults together in a fault system
Faults in red
active during
last 4 million
years
VII. Earthquake Mitigation
A.
B.
C.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake prediction
Long-term forecasting (probabilities of future fault slip)
Pre-historical records
• Geologic investigations; using the “rock record”
to build a history of earthquake activity
• Field of study called paleo-seismology
Reading the geologic record
of past events
Paleo-seismology
Paleo-seismic study in
sediments of a fault sag
pond
Paleo-seismic study in sediments of a fault sag pond
VII. Earthquake Mitigation
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake prediction
A.
B.
C.
Long-term forecasting (probabilities of future fault slip)
•
Based on past behavior
Historical records + pre-historical records + fault mapping = total record
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Recurrence Intervals (Frequency - are we over due?)
Seismic Gaps (Is a fault segment overdue?)
VII. Earthquake Mitigation
A.
B.
C.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake prediction
Long-term forecasting (probabilities of future fault slip)
•
Seismic Gaps (Is a segment of a fault overdue?)
pre-1989 seismic record of San
Andreas fault
1989 Loma Prieta earthquake and aftershocks
Source: USGS
VII. Earthquake Mitigation
A.
B.
C.
Approach to earthquake mitigation
Hazard Identification and Risk Assessment
Earthquake prediction
Short-term warnings
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Radio transmissions faster than seismic waves
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Potential to
 Shutdown public transport such as trains
 Shutoff gas pipelines
 Warn rescuers of aftershocks
 Tsunami warnings
 Use cell phone applications to warn individuals
VII. Earthquake Mitigation
D. Engineering and Building Codes
“Earthquakes don’t kill people buildings do”
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If survivability is the goal, then engineering approaches and
building codes are the main solution
 Reinforced buildings and bridges in earthquake prone areas
 Identify problem soils and avoid them, anchor foundations in
bedrock or use foundation isolators
 Avoid building sites in areas prone to landslides
Images:
NOAA
VII. Earthquake Mitigation
D. Engineering and Building Codes
“Earthquakes don’t kill people buildings do”
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Engineering approaches and building codes require that we know…
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site specific risk levels for ground shaking, including enhanced shaking
(think shake hazard maps)
response of buildings (of varying design) to ground shaking, requires
monitoring shaking in buildings during earthquakes
consider also survivability of occupants vs. survivability of the building for
future use (and how much you are willing to spend)
VII. Earthquake Mitigation
D. Engineering and Building Codes
“Earthquakes don’t kill people buildings do”
•
Engineering approaches and building codes require that we know…
•
•
•
site specific risk levels for ground shaking, including enhanced shaking
(think shake hazard maps)
response of buildings (of varying design) to ground shaking, requires
monitoring shaking in buildings during earthquakes
consider also survivability of occupants vs. survivability of the building for
future use (and how much you are willing to spend)
VII. Earthquake Mitigation
E. Preparation in earthquake prone areas
Emergency preparedness and training is essential to
surviving an earthquake
Coordination among emergency response agencies
Fire, utilities, police, rescue, medical, public transportation
Coordinate communications among emergency response
teams and agencies
Practice exercises – The Great Shake Out
Full scale mock earthquake response exercises
Decentralize emergency supplies and equipment
Earthquake preparation in homes
VII. Earthquake Mitigation
E. Preparation in earthquake prone areas
ShakeMap – Real time
shaking intensity map
product from USGS
Computer generated shake
map (intensity) for a real
earthquake generated
automatically in real time
Allows emergency first
responders to be directed to
areas with greatest needs
without waiting for
emergency calls and first
hand on the ground
accounts