地震 第2輯
Online ISSN : 1883-9029
Print ISSN : 0037-1114
ISSN-L : 0037-1114
兵庫県南部地震に伴って淡路島北西岸に出現した地震断層
粟田 泰夫水野 清秀杉山 雄一井村 隆介下川 浩一奥村 晃史佃 栄吉木村 克己
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ジャーナル フリー

1996 年 49 巻 1 号 p. 113-124

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抄録
Associated with the Hyogo-ken Nanbu earthquake of January 17, 1995 (MJMA 7.2), a 10.5km long surface fault ruptures, the Hokudan Earthquake Fault System, appeared along the Nojima Fault and the Mizukoshi Flexure on the northwest coast of Awaji Island, central Japan. The surface ruptures consist of a NE-SW trending right-lateral fault system with high-angle reverse component. The system has two fault strands, namely the Nojima Earthquake Fault of 8.8km long and the Ogura Earthquake Fault of 3.0km long. These two surface faults show the right-stepping arrangement and form an extensional jog at the southwest of the rupture system. Composite displacement of the right-lateral and vertical shift along the fault system are generally 1.4 to 1.8m (1.2 to 1.6m in right-lateral and 0.5 to 0.8m in vertical). The maximum displacement measures 2.5m (2.1m in right-lateral and 1.3m in vertical) at the central part of the surface faults. At the southwest of the surface ruptures, the fault displacement gradually decreases to non-traceable in a distance of 1.9km. On the other hand, surface ruptures reach as far NE as to the coast of Akashi Strait, about 4km west of the epicenter, with large displacement. No surface rupture appeared in the severely damaged Kobe area, northeast of the epicenter. Geodetic and seismological data suggest that the main faulting event of the earthquake occurred in the Awaji Island area, followed by a smaller event (or events) in the Kobe area. Based on the long-term slip-rate of the Nojima fault in the late Quaternary and the amount of slip of the 1995 event, the recurrence interval of large faulting events is estimated to be 1.3 to 2.5 thousand years.
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© 社団法人日本地震学会
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