Earthquake hazards

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