1995年兵庫県南部地震の地震断層

概要

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Distinctive ruptures of the surface faulting which generated the destructive 1995 Hyogoken-Nanbu Earthquake (M<SUB>s</SUB>=7.2) appeared along the Nojima fault, an active fault on the northwestern coast of Awaji island, Japan. The surface fault ruptures in Awaji island extend southwestward continuously for about 9km from Easki near the epicenter to Toshima in Hokudan town, and caused prominent right-latearl off-sets of 1.9m at maximum on roads, paddy dikes with vertical displacement of 1.2m at maximum, while no large surface faulting has been reported in Kobe where major damage and casualties have appeared.<BR>Most of the surface ruptures follow along the pre-existing active fault traces of the Nojima fault. The ruptures are generally arranged in left-stepping echelon, and local extensional and compressional jog forms such as trenches, mole tracks, buldges are sometimes related to changes in fault strikes.<BR>The earthquake fault seems to have propagated bilaterally northeastward and southwestward from the hypocenter in the Straits of Akashi near the major jog of the earthquake fault system. The source process of the earthquake deduced from the slip distribution along the earthquake fault in Awaji island well explains near-field P-waveforms of broad-band seismometers for early part in about 4 seconds. The later part of much larger amplitude should attribute to the northeast fault ruptures toward Kobe.