中部日本における深発地震の巣とその発震機構

DOI Web Site Web Site

書誌事項

タイトル別名
  • Spatial Clustering and Focal Mechanisms of the Deep Earthquakes in Central Japan
  • チュウブ ニホン ニ オケル シンパツ ジシン ノ ス ト ソノ ハツシン キ

この論文をさがす

抄録

The deep and intermediate-depth earthquakes tend to cluster spatially in the central part of Japan, the corner between the Izu-Bonin and the North-Honshu arcs. Focal mechanism solutions have been determined for the earthquakes in five clusters which are beneath the Sea of Japan, the Wakasa Bay, the Osaka Bay, the Kumanonada and Takayama.<br>Most of the mechanism solutions can be divided into three types in relation to the main feature of the seismic zone and each cluster has its own predominant types of focal mechanism. The axes of maximum compression (P axes) of the earthquakes beneath the Sea of Japan, the Osaka Bay and the Kumanoda dip nearly westwards, though the dip direction of the seismic zone changes from northwest to southwest. There are two types of focal mechanism in these regions according to their directions of the axes of minimum compression (T axes). T axis of one type is perpendicular to the seismic plane while the null axis (B axis) is pararell to the strike of the seismic zone (R-type). The other type has the interchanged B and T axes respect to each other (S-type). R-type is said to be the predominant type for the ‘down-dip compression’ mechanism and the solutions beneath the Osaka Bay seem to have this type but half of the solutions beneath the Sea of Japan and the Kumanoda have S-type. These S-type solutions probably reflect the local change of dip or strike direction of the seismic zone. The solutions beneath the Wakasa Bay and Takayama have a different type focal mechanism of which null axis is pararell to the dip of the seismic zone while T axis is pararell to its strike (N type). These solutions strongly reflect the effects of the arc-junction.

収録刊行物

  • 地震　第２輯

    地震　第２輯 30 (2), 201-212, 1977

    公益社団法人 日本地震学会

詳細情報 詳細情報について

問題の指摘

ページトップへ