HR: 0800h
AN: S21A-0207    [Abstracts]
TI: A New Historical Catalog of Destructive Earthquakes near Tokyo and Implications for the Long-term Seismic Process
AU: * Grunewald, E D
EM: egrunewald@gmail.com
AF: U.S. Geological Survey, 345 Middlefiled Rd MS 977, Menlo Park, CA 94025 United States
AB: In order to expand the temporal span of Japan's seismic record, I construct an intensity-based catalog of damaging earthquakes that struck the greater Tokyo area between 1649 and 1884. Models for fifteen historical earthquakes are developed using calibrated intensity attenuation relations that quantitatively convey uncertainties in event location and magnitude, as well as their covariance. The historical catalog is complete for earthquakes M 6.7 and greater; the largest earthquake in the catalog is the 1703 M~8.2 Genroku event. Seismicity rates from the last 80 years, which include the 1923 M 7.9 Kanto shock, as well as inter-event times estimated from the past ~7000 years of paleoseismic data, are combined with the historical catalog to define a frequency-magnitude distribution for 4.5<M<8.2, which is well described by a truncated Gutenberg-Richter relation with a b-value of 0.96 and a maximum magnitude of 8.4. Uncertainties associated with the intensity-based catalog are propagated by a Monte Carlo simulation to calculate the scalar moment rate. The resulting best estimate of moment rate during 1649-2003 is 1.24 (-0.11, + 0.63) x 10²⁰ N m yr^-1. Comparison with geodetic models of the interseismic deformation indicates that the geodetic moment accumulation and catalog moment release rates are balanced. This balance implies that the extended catalog is representative of long-term seismic processes near Tokyo, and so can be used to assess earthquake probabilities. The resulting Poisson (or time-averaged) 30-yr probability for M 7.9 earthquakes is 7-11%.
DE: 7200 SEISMOLOGY
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Seismology [S]
MN: Fall Meeting 2005