Keywords:Morimoto fault, seismic reflection profiling, active fault
To estimate seismic hazards, understanding the relationship between active fault and seismic source fault is crucial. To estimates seismic hazards, more detailed survey to identify source faults is needed. A research project funded by MEXT named "the integrated research project on seismic and tsunami hazards around the Sea of Japan" began in FY 2013. To obtain the information of a seismogenic source fault, we performed seismic reflection profiling across the Morimoto fault, north eastern boundary fault of the Kanazawa plain. This fault is northern part of the Morimoto-Togashi fault zone, extend for 26-km along the eastern boundary of the Kanazawa plain (Active fault Research Group, 1991; Togo et al., 1998). The length of seismic line is approximately 9 km. We used a medium size vibrator truck (IVI Envirovib). We deployed 10 Hz geophones at 10 m interval covering whole seismic line. The sweep signals (8-100Hz for high resolution reflection profiling, 8-40Hz for refraction profiling) were recorded by fixed 885 channels. The seismic data were processed using conventional CMP-reflection methods and refraction tomography (Zelt & Barton, 1998). Seismic section portrays the image down to 1.5 seconds (TWT). The resultant depth converted seismic section show a simple monocline produced by an east-dipping reverse fault. A vertical separation by this fault is about 700 m. Judging from the horizontal reflectors on the hanging wall, fault geometry shows simple plane with constant dip angle.