Earthquake loss estimation and planning scenarios quantify seismic risk based on seismic hazard and exposure and vulnerability of the built environment. Such studies need to be frequently updated because of continuing development of the built environment and evolving technology in earthquake ground motion prediction and seismic hazard assessments. California Geological Survey (CGS) has developed and participated in the development of many planning scenarios since 1980. CGS also updates its scenario- and probabilistic-based loss estimations when significant developments occur in ground motion hazard analyses and in built environment.
Using HAZUS default information for built environment and demographics, CGS studied statewide annualized earthquake losses (AEL) based on standard seismic hazard models developed by CGS and United States Geological Survey (USGS) for the National Seismic Hazard Maps. The annualized loss estimation incorporated the effect of local soil conditions using current ground motion prediction equations. AELs were estimated at three levels of geographic resolution: census tract, county, and Metropolitan Statistical Area (MSA). Our calculations show that the lower ground motions predicted by the newer ground motion prediction equations translate directly to substantially lower annual earthquake loss estimations in California (see a brief summary or download CGS Special Report SR 222).
CGS studied potential losses due to scenario earthquakes. Each scenario includes estimates of damage, casualties and other consequences of the scenario earthquake. In northern California the three most damaging scenario earthquakes involve co-seismic rupture of different combinations of segments of the San Andreas Fault, with estimated economic losses ranging from nearly $70 billion to over $80 billion. In southern California, the most damaging scenario is the M7.1 earthquake on the Puente Hills Fault, with up to 30% building loss in some census tracts and total predicted building loss of $79 billion ($82.8 billion in total economic loss). Similarly to the results for AEL, calculated losses for scenarios are significantly lower when current ground motion prediction equations are used to develop the scenario ground shaking. The 2009 work was supported by California Emergency Management Agency (see a brief summary or download project report or CGS Special Report SR 222).
CGS estimated scenario earthquake losses in ten counties in the San Francisco Bay Area and in ten counties in Southern California using scenario ground motions of fifty potential earthquakes published by the United States Geological Survey (USGS). CGS also estimated statewide annualized earthquake losses using the 2002 PSHA maps for the State of California, prepared and published by CGS and USGS. These analyses used HAZUS Service Release 2 default information for built environment and demographics. HAZUS is a loss estimation software package developed by the Federal Emergency Management Agency. The 2005 work was supported by CGS. See Exclusive Summary for major findings and links to the detailed results for all earthquake scenarios and for statewide annualized earthquake losses or see Complete Paper for detailed technical discussions.
Other CGS Publications
Cao, T. (2007). Disaggregation of seismic hazard extended to disaggregation of annualized loss ratio, Bulletin of the Seismological Society of America, v 97, 305-317.
Cao, T. and M.D. Petersen (2006). Uncertainty of earthquake losses due to model uncertainty of input ground motions in the Los Angeles area, Bulletin of the Seismological Society of America, v 96, 365-376.
Cao T., M.D. Petersen, C.H. Cramer, T.R. Toppozada, M.S. Reichle, and J.F. Davis (1999). The calculation of expected loss using probabilistic seismic hazard, Bulletin of the Seismological Society of America, v 89, 867-876.
Earthquake Planning Scenarios published by the California Geological Survey