HR: 16:45h
AN: NG54A-04    [Abstracts]
TI: Do earthquakes correlate better with Earth tides in earthquake prediction windows?
AU: Shebalin, P N
EM: shebalin@mitp.ru
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Warshavskoye sh. 79 kor. 2, , Moscow, 113556 Russian Federation
AU: * Cochran, E S
EM: cochran@moho.ess.ucla.edu
AF: University of California, Los Angeles, 595 Charles Young Drive, Los Angeles, CA 90095 United States
AU: Vidale, J E
EM: vidale@moho.ess.ucla.edu
AF: University of California, Los Angeles, 595 Charles Young Drive, Los Angeles, CA 90095 United States
AU: Keilis-Borok, V
EM: vkb@ess.ucla.edu
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Warshavskoye sh. 79 kor. 2, , Moscow, 113556 Russian Federation
AU: Keilis-Borok, V
EM: vkb@ess.ucla.edu
AF: University of California, Los Angeles, 595 Charles Young Drive, Los Angeles, CA 90095 United States
AB: Recent work has inferred that seismicity correlates best with Earth tides in the months prior to large magnitude events (Tanaka, Fall AGU meetings, 2003, 2004). These results suggest that the crust approaches a critical state in which even small tidal stress perturbations can trigger seismicity before a large earthquake, or perhaps both the tides and seismicity are affected by a third factor such as crustal strength. We examine seismicity that occurs within the space-time alarm windows defined using the prediction methods of Keilis-Borok et al. (1996, 2004). The methods poll a variety of measures to find precursors and statistical anomalies in earthquake catalogs. When a sufficient number of indicators pass a threshold, an increased probability of an earthquake occurring is assigned to a given region and time. We will measure the correlation of seismicity with Earth tides in the M7.5 and M8 increased probability windows that have been established since 1985. We will use all available windows, whether or not each resulted in successful predictions, to determine if earthquakes are more likely to correlate with tides during times of anomalous seismicity. Statistically stronger tidal correlation seen in an alarm window would suggest the crust is in a critical regime. If it is a robust signal, tidal correlation could be incorporated as an additional precursor for short-term earthquake prediction as a way to more precisely define the spatial and temporal extent of the prediction windows.
DE: 7223 Seismic hazard assessment and prediction
DE: 7200 SEISMOLOGY
DE: 3200 MATHEMATICAL GEOPHYSICS (New field)
DE: 1249 Tides--Earth
DE: 1255 Tides--ocean (4560)
SC: Nonlinear Geophysics [NG]
MN: 2004 AGU Fall Meeting