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| | Abstract | | The deep geometry of active faults and the mid-crustal detachment at the base of seismogenic layer is important for understanding active tectonic process and accessing the risk of destructive earthquakes. To investigate the deeper extension of active faults within the seismogenic layer, we conducted a seismic reflection profiling experiment across the western marginal faults of Kitakami lowland, northeast Japan. The combination of telemetry and independent recording system has provided the deployment of wide-angle survey line with dense seismic array. The simultaneous data acquisition of regional refraction, low-fold wide-angle reflection and dense reflection survey has been optimized by the integration of vibrator source focused on effective low-frequency bandwidth of sweep signal and the three-component digital accelerometers with broader frequency responses. The seismic reflection profile shows that the deeper extension of the western marginal faults of Kitakami lowland converges on the mid-crustal detachment. Along the reflection survey line, a dense seismic array with the combination of short-period seismometers and digital accelerometers was deployed for teleseismic and local-earthquake observation. We utilized multimode prestack migration for receiver function and interferometric seismic imaging for back scattered phases to investigate the lower crustal structure and Moho boundary. |
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