Project Abstract
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This research project examines the variation of annualized loss estimates predicted for California using the Federal Emergency Management Agency’s Hazus (Hazards U.S.) natural hazard risk assessment software and seismic hazard data developed with several different variants (i.e., logic tree branches) of the time independent Uniform California Earthquake Rupture Forecast Version 3 (UCERF3). Eleven statewide annualized loss analyses have been conducted using Hazus-MH Maintenance Release 4, evaluating the difference in losses associated with the various UCERF3 deformation models, off-fault spatial seismicity models, and earthquake rupture forecast (UCERF3 vs. UCERF2). The resulting variation in statewide annualized loss across the various UCERF3 models is modest; the selection of the Geologic Deformation Model (DM) results in annualized statewide losses 1% greater that losses for the Zeng DM (Reference Branch, RB), while the AveBlockModel DM produces losses 1% lower than the RB. The net difference is larger for the NeoKinema DM (3% less than the RB), and selection of the UCERF2 off-fault seismicity model produces statewide losses 5% less than the RB. Differences between losses estimated with UCERF2 and the UCERF3 RB are more significant; statewide annualized losses estimated using UCERF3 are 9% less than UCERF2 losses, before soil amplification factors are applied. While the net statewide difference in loss between two models may be small, regional differences can be much larger. Differences in county-level annualized building damage ranged from -17% to 15% for the Geologic DM (relative to the RB), -71% to 22% for the AveBlockMod DM, -41% to 21% for the NeoKinema DM, -38 to 61% for the UCERF2 off-fault seismicity model, and -61% to 63% for the UCERF2 earthquake rupture forecast. |
