SMGA and Short-period Spectral Level of the Historical Earthquakes around Tokyo Metropolitan Area Inferred from Seismic Intensity Inversion Analysis

Abstract

The strong motion generation areas of major historical earthquakes of the Tokyo metropolitan area such as the 1703 Genroku, the 1855 Ansei-Edo and the 1923 Great Kanto earthquakes are obtained using seismic intensity inversion analysis based on the attenuation relationship and site factors derived from recent measured intensity data. The short-period spectral level of acceleration source spectra is estimated from the empirical relational expression with normalized seismic intensity level based on the seismic intensity inversion results. Although the 1703 Genroku and the 1923 Great Kanto earthquakes along the Sagami Trough are similar in magnitude and short-period spectral level, the strong motion generation areas related to seismic intensity are found to be different. The 1855 Ansei-Edo earthquake is estimated to occur about 40 km deep in northern Tokyo Bay and to be a little bit smaller than the other two earthquakes.