SCEC Award Number 09138 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title California Earthquake Forecasts
Investigator(s)
Name Organization
David Jackson University of California, Los Angeles
Other Participants Kagan, Yan Y.
Wang, Qi
SCEC Priorities A4, A6 SCEC Groups Seismology, EFP, WGCEP
Report Due Date 02/28/2010 Date Report Submitted N/A
Project Abstract
 We will prepare three earthquake forecasts for the California and Nevada region for testing in the CSEP (Collaboratory for Study of Earthquake Predictability) project. The three forecasts will be (1) a long-term forecast based on our special catalog of historic and instrumental earthquakes since 1800 (2) a long term catalog based on recent instrumentally recorded
earthquakes, and (3) a short-term forecast based on the instrumentally recorded earthquakes. We have two major objectives. First is to develop forecasting and testing techniques that can confirm or reject important hypotheses like earthquake clustering, elastic rebound, fault-limited magnitudes, region variation of b-value, etc. Second, we plan to develop an earthquake forecast that has withstood some testing for use in the next round of estimates by the Working Group on California Earthquake Probabilities. All forecasts would be expressed as earthquake rate density (probability per unit area, time, and magnitude) on a 0.1 degree grid for a region including
California and Nevada, based only on data from past earthquakes. Our long-term forecasts are not explicitly time-dependent, but they can be updated at any time to incorporate information from recent earthquakes. The present version, founded on several decades worth of data, is suitable for testing without updating over a five-year period. The short-term forecast is meant to
be updated daily and tested against similar models by CSEP. The short-term forecast includes a fraction of our long-term one plus time-dependent contributions from all previous earthquakes. Those contributions decrease with time according to the Omori law: proportional to the reciprocal of the elapsed time. All forecasts estimate rate density using a radially symmetric
spatial smoothing kernel decreasing approximately as the reciprocal of the square of epicentral distance, weighted according to the magnitude of each past earthquake.