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Toward System-Level Earthquake Probability Modeling: Karen Felzer
Project Title: Toward System-Level Earthquake Probability Modeling
Mendenhall Fellow: Karen Felzer, (626) 583-7822,
Duty Station: Pasadena, California
Start Date: March 31, 2005
Education: Ph.D. (Earth and Planetary Sciences), Harvard University, 2003
Research Advisors: Ned Field, (626) 583-7814,; Thomas Jordan, (213) 821-1237,

Project Description: As the newly released USGS Short Term Earthquakes Probability map (STEP) (Gerstenberger, Wiemer, Jones, and Reasenberg) will tell you, it’s quite easy to forecast when a M>6 earthquake will hit Southern California: right after an M>7 earthquake has occurred. Although there has been a recent upsurge of interest in new methods of earthquake forecasting/predictability, the strongest and the only verified method of earthquake forecasting remains carefully applying the empirical rules that govern how earthquakes trigger each other. The focus of this project will be to increase our understanding of earthquake triggering in order to improve both our ability to make forecasts using earthquake triggering statistics and to help us gain an understanding of the physics of the aftershock triggering process.

In the area of forecasting the project will investigate the critical issue of how much the probability of triggering a large earthquake does (or does not) increase when a smaller earthquake happens near a large fault such as the San Andreas. It will also investigate the distances to which earthquakes can be triggered by mainshocks of all magnitudes, the differences between triggering in volcanic and non-hydrothermal areas, and the length of time over which triggering significantly perturbs expected earthquake rates from the long term average. The last question has particular importance with respect to how effectively aftershock statistics might be used in the production of annually released time-dependent earthquake forecasts. While aftershock-based earthquake forecasts updated on a daily or hourly basis, such as STEP is, will always be more accurate, there is a need for longer term
forecasts for annual preparedness and policy making decisions. It is hoped that this work might contribute to the newly formed, statewide Working Group on California Earthquake Probabilities.

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Last modified: 16:08:28 Thu 13 Dec 2012