HR: 1340h
AN: NG23C-0102    [Abstracts]
TI: From Tornadoes to Earthquakes: Forecast Verification for Binary Events Applied to the 1999 Chi-Chi, Taiwan, Earthquake
AU: Chen, C
EM: ChenCC@cse.ucdavis.edu
AF: National Central University, Dept. Earth Sciences, Taipei, 320 Taiwan
AU: * Rundle, J B
EM: jbrundle@ucdavis.edu
AF: University of California, Center for Computational Science, Davis, CA 95616 United States
AU: Holliday, J R
EM: holliday@cse.ucdavis.edu
AF: University of California, Center for Computational Science, Davis, CA 95616 United States
AU: Nanjo, K
EM: nanjo@cse.ucdavis.edu
AF: Institute for Statistical Mathematics, Minato-ku, Tokyo, 106-8569 Japan
AU: Turcotte, D L
EM: turcotte@geology.ucdavis.edu
AF: University of California, Dept of Geology, Davis, CA 95616 United States
AU: Li, S
EM: li@cse.ucdavis.edu
AF: National Central University, Dept. Earth Sciences, Taipei, 320 Taiwan
AU: Tiampo, K F
EM: kftiampo@uwa.edu.ca
AF: University of Western Ontario, Dept of Earth Science, London, ON N6A5B7 United States
AB: Forecast verification procedures for statistical events with binary outcomes typically rely on the use of contingency tables and Relative Operating Characteristic (ROC) diagrams. Originally developed for the statistical evaluation of tornado forecasts on a county-by-county basis, these methods can be adapted to the evaluation of competing earthquake forecasts. Here we apply these methods retrospectively to two forecasts for the m = 7.3 1999 Chi-Chi, Taiwan, earthquake. These forecasts are based on a method, Pattern Informatics (PI), that locates likely sites for future large earthquakes based on large change in activity of the smallest earthquakes. A competing null hypothesis, Relative Intensity (RI), is based on the idea that future large earthquake locations are correlated with sites having the greatest frequency of small earthquakes. We show that for Taiwan, the PI forecast method is superior to the RI forecast null hypothesis. Inspection of the two maps indicates that their forecast locations are indeed quite different. Our results confirm an earlier result suggesting that the earthquake preparation process for events such as the Chi-Chi earthquake involves anomalous changes in activation or quiescence, and that signatures of these processes can be detected in precursory seismicity data. Furthermore, we find that our methods can accurately forecast the locations of aftershocks from precursory seismicity changes alone, implying that the main shock together with its aftershocks represent a single manifestation of the formation of a high-stress region nucleating prior to the main shock.
DE: 0550 Model verification and validation
DE: 3238 Prediction (3245, 4263)
DE: 4430 Complex systems
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005