HR: 14:10h
AN: S43D-03    [Abstracts]
TI: Exaggerated Claims About Success Rate of Earthquake Predictions: "Amazing Success" or "Remarkably Unremarkable"?
AU: Kafka, A L
EM: kafka@bc.edu
AF: Weston Observatory, Boston College 381 Concord Rd., Weston, MA 02493 United States
AU: * Ebel, J E
EM: ebel@bc.edu
AF: Weston Observatory, Boston College 381 Concord Rd., Weston, MA 02493 United States
AB: On October 1, 2004, NASA announced on its web site, "Earthquake Forecast Program Has Amazing Success Rate." This announcement claimed that the Rundle-Tiampo earthquake forecast method has accurately predicted the locations of 15 of California's 16 largest earthquakes this decade. Since words like "amazing" carry a lot of meaning to consumers of scientific information, claims of "amazing success" should be limited only to cases where the success is truly amazing. We evaluated the statistical likelihood of the reported success rate of the Rundle-Tiampo prediction method by applying a cellular seismology approach to investigate whether proximity to past earthquakes is a sufficient hypothesis to yield the same level of success as the Rundle-Tiampo method. To delineate where to expect future earthquakes, we used the epicenters of the ANSS earthquake catalog for California from 1932 through 1999 with magnitude≥4.0 ("before" earthquakes). We then tested how many of the 15 events that are shown on the NASA web page ("after" earthquakes) occurred near the "before" earthquake epicenters. We found that with only a 4 km radius around each "before" earthquake epicenter, we successfully forecast the locations of 13/15 (87%) of the "after" earthquakes, and with a 7 km radius we successfully forecast 14/15 (93%) of the earthquakes. The zones created by filling in a 7 km radius around the "before" epicenters cover 18% of the study area. The scorecard maps on the JPL "QuakeSim" web site show an 11 km margin of error for the epicenters of the forecast earthquakes. With an 11 km radius around the past epicenters (covering 31% of the map area), we catch 14/15 of the "after" earthquakes. We conclude that the success rate referred to in the NASA announcement is perhaps better characterized as "remarkably unremarkable", rather than "amazing." The 14/15 success rate for the earthquakes listed on the NASA scorecard is not a rigorous test of the Rundle-Tiampo method, since it appears that any method that uses past seismicity maps as a basis for earthquake forecasting should have a comparable rate of success.
DE: 6620 Science policy (0485)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005