Permalink : http://hdl.handle.net/2115/44469

JaLCDOI : 10.14943/gbhu.73.137

On August 11, 2009, an intraplate earthquake （MJMA 6.5） occurred within the subducting Philippine Sea slab beneath Suruga Bay at a depth of 23 km. The source model composed of two strong motion generation areas（SMGA）has been estimated by the broadband strong motion simulation using the empirical Green's function method in the frequency range between 0.3 Hz and 10 Hz. The stress drop of each SMGA is estimated to be 35.7 MPa and 27.5 MPa. The rupture of SMGA 1 on the southeast dipping fault plane mainly propagated southwestward, and that of SMGA 2 on the northeast dipping fault plane propagated northwestward. The obtained source model explains the observed acceleration, velocity, and displacement waveforms of this event in the broadband frequency range fairly well. Then, the size of SMGA for the 2009 Suruga Bay earthquake is compared with the scaling relationship by previous studies on other intraslab and inland crustal earthquakes. The size of SMGA for intraslab earthquakes in the previous studies is generally smaller than that for inland crustal earthquakes. In contrast, the SMGA of the 2009 Suruga Bay earthquake is almost comparable to the empirical scaling relationship for inland crustal earthquakes. That difference is mainly because the relatively shallower source depth of this event compared to other intraslab earthquakes. For advanced strong motion prediction for intraslab earthquakes, it could be necessary to adopt depth-dependency and regional differences in stress drop on SMGA or asperity in the source modeling.