Earthquake hazards  Ground Rupture Ground rupture from the M 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

Seismic Hazard of MA

Cape Ann Earthquake 1755 Woodcut illustration depicting damage in Boston from the earthquake

Hazard vs risk z1989 Macquarie Ridge, New Zealand yM 8.3 yNo losses z1960 Agadir, Morocco yM 5.5 y12,000 deaths

Earthquake Risk zRisk = hazard x vulnerability zThe amount of damage and numbers of earthquake related deaths do not correlate to magnitude of the earthquake.

Products of hazard assessment zActive fault map zHistorical seismicity zEarthquake likelihood

3D models assess seismic hazard in Los Angeles, CA SCEC Community Fault Model

Acceptable Risk zLevel of acceptable risk depends on the structure zCannot design for maximum earthquake with low probability zSocial question

How would you mitigate damages from…. zGround Rupture zLiquefaction zGround Shaking zTsunami

Ground Rupture zAvoid construction zRelocate sensitive facilities zImplement low use facilities yPlaying fields yGreen space

Portola Valley California

Liquefaction zRecognize liquefaction potential zIn-situ remediation zAvoid construction in liquefaction prone areas

Tsunami mitigation zEarly warning system yBroadcast signal to beaches after a major earthquake anywhere in the ocean basin zSaftey guidelines yGo to high ground yClimb a tree

Ground Shaking zRecognize the degree of probable ground shaking in the area zImprove construction methods to accommodate shaking without collapse