Losses to Single-Family Housing from Ground Motions in the 1994 Northridge, California, Earthquake

The distributions of insured losses to single-family housing following the 1994 Northridge, California, earthquake for 234 ZIP codes can be satisfactorily modeled with gamma distributions. Regressions of the parameters in the gamma distribution on estimates of ground motion, derived from ShakeMap estimates or from interpolated observations, provide a basis for developing curves of conditional probability of loss given a ground motion. Comparison of the resulting estimates of aggregate loss with the actual aggregate loss gives satisfactory agreement for several different ground-motion parameters. Estimates of loss based on a deterministic spatial model of the earthquake ground motion, using standard attenuation relationships and NEHRP soil factors, give satisfactory results for some ground-motion parameters if the input ground motions are increased about one and one-half standard deviations above the median, reflecting the fact that the ground motions for the Northridge earthquake tended to be higher than the median ground motion for other earthquakes with similar magnitude. The results give promise for making estimates of insured losses to a similar building stock under future earthquake loading.

[1]  James F. Davis,et al.  The calculation of expected loss using probabilistic seismic hazard , 1999 .

[2]  M. Evans.  Statistical Distributions , 2000 .

[3]  Thomas H. Heaton,et al.  TriNet “ShakeMaps”: Rapid Generation of Peak Ground Motion and Intensity Maps for Earthquakes in Southern California , 1999 .

[4]  J. Boatwright,et al.  Correlation of Ground Motion and Intensity for the 17 January 1994 Northridge, California, Earthquake , 2001 .

[5]  Karl V. Steinbrugge,et al.  Earthquake losses to single-family dwellings; California experience , 1990 .

[6]  Charles A. Kircher,et al.  Estimation of Earthquake Losses to Buildings , 1997 .

[7]  S. T. Algermissen,et al.  A probabilistic estimate of maximum acceleration in rock in the contiguous United States , 1976 .

[8]  Charles A. Kircher,et al.  Development of Building Damage Functions for Earthquake Loss Estimation , 1997 .

[9]  W. B. Joyner,et al.  Equations for Estimating Horizontal Response Spectra and Peak Acceleration from Western North American Earthquakes: A Summary of Recent Work , 1997 .

[10]  D. Perkins,et al.  National Seismic-Hazard Maps: Documentation June 1996 , 1996 .

[11]  William A. Bryant,et al.  Probabilistic seismic hazard assessment for the state of California , 1996 .

[12]  Thomas H. Heaton,et al.  Relationships between Peak Ground Acceleration, Peak Ground Velocity, and Modified Mercalli Intensity in California , 1999 .

[13]  David M. Perkins,et al.  Spatial Correlation of Probabilistic Earthquake Ground Motion and Loss , 2001 .

[14]  William A. Bryant,et al.  A Site-Conditions Map for California Based on Geology and Shear-Wave Velocity , 2000 .