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Earthquake hazards
Ground Rupture
Ground rupture from the M8.1 2001 Tibet earthquake
Alaskan pipe after the Denali quake ruptured through
Earthquake hazards (cont.)
Shaking Wave
amplitude Wave
frequency Duration of
shaking
Earthquake hazards (cont)
Liquefaction Saturated sand
loses strength upon shaking
1964 Nigata Japan
Tsunami Wave wavelength
ocean waves that can travel vast distances
2004 Sumatra earthquake
Sumatra Earthquake tsunami
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
QuickTime™ and aVideo decompressor
are needed to see this picture.
Seismic Hazard of MA
Cape Ann Earthquake 1755
Woodcut illustration depicting damage in Boston from the earthquake
Hazard vs risk
1989 Macquarie Ridge, New Zealand M 8.3 No losses
1960 Agadir, Morocco M 5.5 12,000 deaths
Earthquake Risk
Risk = hazard x vulnerabilityThe amount of damage and numbers of
earthquake related deaths do not correlate to magnitude of the earthquake.
Products of hazard assessment
Active fault mapHistorical seismicityEarthquake likelihood
3D models assess seismic hazard in Los Angeles, CA
SCEC Community Fault Model
Acceptable Risk
Level of acceptable risk depends on the structure
Cannot design for maximum earthquake with low probability
Social question
How would you mitigate damages from….
Ground RuptureLiquefactionGround ShakingTsunami
Ground Rupture
Avoid constructionRelocate sensitive facilitiesImplement low use facilities
Playing fields Green space
Portola Valley California
Liquefaction
Recognize liquefaction potentialIn-situ remediationAvoid construction in liquefaction prone
areas
Tsunami mitigation
Early warning system Broadcast signal to beaches after a major
earthquake anywhere in the ocean basin
Saftey guidelines Go to high ground Climb a tree
Ground Shaking
Recognize the degree of probable ground shaking in the area
Improve construction methods to accommodate shaking without collapse