干渉SARによって得られた地表変位の勾配解析による1995年兵庫県南部地震の地表断層位置推定

Abstract

The 1995 Hyogo-ken Nanbu earthquake in Japan caused large crustal deformation, however, only a few exposed faults have been identified by ground survey and detailed positions of the earthquake faults have not been mapped. The displacement field on the surface associated with the earthquake was mapped by a satellite radar interferometry image. The Synthetic Aperture Radar (SAR) interferogram generally shows elastic motion caused by the main earthquake but many discontinuities of the fault displacements are found, the latter of which can be most easily visualized in the surface displacement gradient. During the earthquake a concentration of damage, so-called damage belt, was observed. Though we found displacements probably caused by hidden faults just under the damage belt, the hidden faults were shorter in length and their displacements were smaller than those of the known faults running along the northern edge of the damage belt. However, strong seismic vibration was observed just on the small faults found in surrounding area of the main faults. Accordingly there is some possibility that the hidden small faults accelerated the main seismic vibration.