<特別寄稿>活断層での観測・実験・研究とともに --野島断層・山崎断層・跡津川断--

Abstract

This paper summarizes the studies on three active faults, which the author has carried out through extensive observations and experiments. First, the Nojima fault is one part of the earthquake source fault of the 1995 Hyogo-ken Nanbu earthquake (M 7.3), and its healing process after the earthquake was studied by repeated water-injection experiments using three boreholes drilled through or close to the fault. We observed fault-zone trapped waves for injection-induced and background ultra-microearthquakes, and estimated deep structure of the Nojima fault. The second is the observation and analysis of typical fault-zone trapped waves in the subsurface survey tunnel excavated through the Mozumi-Sukenobe fault, one part of the Atotsugawa fault zone. The third is the Yamasaki fault zone. We estimated 3-D image of scattering strength around the fault by analyzing coda waves observed by dense temporary and routine seismic stations. We also studied generating properties of micro to small-scale earthquakes in heterogeneous source area.