横手盆地東縁断層帯・千屋断層(運上野)を横断する浅層反射法地震探査(2004年) : データ取得と処理について

概要

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The 1896 Rikuu earthquake (M=7.2) was generated at the eastern margin of the Yokote basin fault zone which was composed of four surface ruptures: Obonai, Shiraiwa, Ota, and Senya faults. The Senya fault is a major rupture exemplified by front migration of thrusting, and has a flat-ramp structure at the central part of the rupture. It is thought that the above-mentioned structure has been transforming along the fault trace because the Senya fault has a bow-shaped trace with changes of tectonic features between the northern and central parts. We conducted a high-resolution seismic reflection profiling survey across the northern part of the Senya fault and nearby tectonic structures. The obtained seismic reflection data were processed by conventional common mid-point stacking, post-stack migration, and depth conversion. As a result, it was revealed that the subsurface structure of the northern part of the Senya fault consists of two major faults and complex fold structure in the hanging wall. The Senya fault with some subsidiary faults is concealed.
東京大学の論文
2007-03-14