活断層周辺の地震活動の定量的な評価-GISデータベースの作成と活用-

Abstract

活断層周辺の地震活動を解析することは, 大地震の予知に重要な課題である。「微小地震データ」と「気象庁地震データ」からGISデータベース作成し, 断層からの距離をパラメーターとして地震発生密度を計算した。その変化から断層の影響を受ける距離(支配領域)を求めた。気象庁データでは15断層(22断層域), 微小地震データでは11断層について解析を行い, それぞれ7地震域と6断層について, 支配距離はそれぞれ約3kmと4kmと求まった。

To analyze seismic activity around active fault has an important role to clarify earthquake mechanism and to earthquake prediction. The examination by GIS data that is obtained from earthquake data was carried out. The area and the number of earthquake are found with the distance from active fault as a parameter, and the generation density of earthquake per unit area was calculated. The distance that is dominated by a fault (dominated area) was found by the variation of the earthquake generation density. 15 faults (22 seismic area) from the JMA data and 11 faults from the microearthquake data were analyzed. The seismic activities of the 7 seismic areas and the 6 faults can be clearly picked up and the activity degree of these was obtained. The seismic activity that is dominated by the fault is found to be 3-4 km from the fault. Accordingly, it is cleared that the seismic activities around the fault and the epicenter's fault of a big earthquake only dominate a limited area.