地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
注水に伴う誘発地震の発生特性
野島断層注水実験を中心として
西上 欽也田所 敬一永井 悟水野 高志加納 靖之平松 良浩
著者情報
ジャーナル フリー

2002 年 111 巻 2 号 p. 268-276

詳細
抄録

This paper briefly reviews the triggering characteristics of injection-induced seismicity. Water injection experiments were carried out in the Nojima fault, southwest Japan in 1997 and 2000 to detect the healing process of the fault zone after being ruptured by the MJMA 7.3 Hyogo-ken Nanbu (Kobe) earthquake in 1995. During the experiment in 2000, ultramicroearthquakes of M-1.2 to 1.0 were induced at about 2.5-4.5 km from the injection point and about 4-6 days after the beginning of injection. This space-time migration can be explained by a 2-D diffusion process of pore water pressure. Permeability estimated near the surface, at about 540-800 m depth, is extrapolated well to a depth of 2-4 km where induced events occurred. Other experiments at Matsushiro, central Japan and KTB, Germany also showed similar space-time relationships of induced seismicity. From observations in the Nojima experiment, we obtained characteristic states that suggest differences in the generating process between induced and normal (tectonic) earthquakes. Our findings are as follows : (1) high-frequency component is richer in the waveforms of tectonic events, and (2) the clustering of hypocenters is more dominant in induced events. Further analyses of these observations will lead to elucidating the generating process of induced earthquakes by increasing pore water pressure.

著者関連情報
© Copyright (c) 東京地学協会
前の記事 次の記事
feedback
Top