link to main US Geological Survey website
U.S. Geological Survey
Open-File Report 2006-1020
Version 1.0

Sensitivity of Earthquake Loss Estimates to Source Modeling Assumptions and Uncertainty

By Paul A. Reasenberg, Nan Shostak, and Sharon Terwilliger


thumbnail view of map
Ground motions and direct economic loss caused by rupture of the entire San Andreas fault (segments SAS+SAP+SAN+SAO, magnitude 7.9) (from figure A4).

This report explores how uncertainty in an earthquake source model may affect estimates of earthquake economic loss. Specifically, it focuses on the earthquake source model for the San Francisco Bay region (SFBR) created by the Working Group on California Earthquake Probabilities. The loss calculations are made using HAZUS-MH, a publicly available computer program developed by the Federal Emergency Management Agency (FEMA) for calculating future losses from earthquakes, floods and hurricanes within the United States. The database built into HAZUS-MH includes a detailed building inventory, population data, data on transportation corridors, bridges, utility lifelines, etc. Earthquake hazard in the loss calculations is based upon expected (median value) ground motion maps called ShakeMaps calculated for the scenario earthquake sources defined in WGCEP.

The study considers the effect of relaxing certain assumptions in the WG02 model, and explores the effect of hypothetical reductions in epistemic uncertainty in parts of the model. For example, it addresses questions such as what would happen to the calculated loss distribution if the uncertainty in slip rate in the WG02 model were reduced (say, by obtaining additional geologic data)? What would happen if the geometry or amount of aseismic slip (creep) on the region's faults were better known? And what would be the effect on the calculated loss distribution if the time-dependent earthquake probability were better constrained, either by eliminating certain probability models or by better constraining the inherent randomness in earthquake recurrence?

The study does not consider the effect of reducing uncertainty in the hazard introduced through models of attenuation and local site characteristics, although these may have a comparable or greater effect than does source-related uncertainty. Nor does it consider sources of uncertainty in the building inventory, building fragility curves, and other assumptions adopted in the loss calculations. This is a sensitivity study aimed at future regional earthquake source modelers, so that they may be informed of the effects on loss introduced by modeling assumptions and epistemic uncertainty in the WG02 earthquake source model.

Download this publication as a PDF file (of2006-1020.pdf; 33 pages, 3.9 MB)

For questions about the content of this report, contact Paul Reasenberg

Version history

Download a copy of the latest version of Adobe Reader for free.

| Help | PDF help | Publications main page | Open-File Reports for 2006 |
| Geologic Division | Earthquake Hazards Program |

This report is available only on the web.

| Department of the Interior | U.S. Geological Survey | Privacy Statement | Disclaimer | Accessibility |
URL of this page:
Maintained by: Michael Diggles
Created: February 27, 2006
Last modified: February 28, 2006 (mfd)