強震記録に基づくフィリピン海プレート内で発生するスラブ内地震の高振動数成分の励起特性 : 北海道・東北地方のスラブ内地震との比較

概要

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Acceleraion source spectra of intra-slab earthquakes in the Philippine Sea plate were evaluated by eliminating the path and site effects from observation records. High-frequency levels M_<HF> were evaluated from the acceleration source spectra, and stress parameters Δσ were calculated from M_<HF> and seismic moment M_O. The relationships between Δσ and M_O and Δσ and focal depth were examined and compared with those of the Pacific plate. Upper level of Δσ is not affected by M_O and is 40-80MPa. But lower level of Δσ is affected by M_O, that is, lower than 5MPa for small earthquakes (Mw<5.7), 20-80MPa for medium earthquakes (5.7<Mw<6.6), and 60-80MPa for large earthquakes (Mw>6.6). And, lower levek of Δσ are different to each other for large earthquakes of two plates. Δσ is constant to focal depth for medium and large earthquakes.
2004-12-30