Three-Dimensional S-Wave Velocity Structure of the Kinki Region, Southwestern Japan based on Ambient Seismic Noise Tomography using Data from Dense Seismic Array
Year: 2021
Type: preprint
Abstract: Research interest in the Kinki region, southwestern Japan, has been aroused by the frequent occurrence of microearthquake activity, particularly on the northern side of the Arima-Takatsuki Tectonic Line. Previous studies in this area focused mainly on deep, large-scale structures and could not efficiently resolve fine-scale (~10 km) shallow crustal structures. Hence, characterization of the upper crustal structure of this region at an improved spatial resolution is required. By cross-correlating the vertical components of the continuous ambient seismic noise data from a dense seismic array, we estimated Rayleigh wave phase velocities using a frequency domain method. The 3D S-wave velocity structure of the Kinki region was then obtained by applying a direct surface wave tomographic method for the phase velocity dispersion data. The estimated velocity model reveals a NE-SW trending low-velocity structure coinciding with the Niigata-Kobe Tectonic Zone (NKTZ) and the active Biwako-seigan Fault Zone (BSFZ). Also, we identified fine-scale low-velocity structures coinciding with known active faults on the eastern side of the NKTZ, as well as sets of low-velocity structures across the Tanba region, that may be attributable to the weathering effects or activity of unidentified concealed fault zones. Furthermore, sedimentary basins manifest as low-velocity zones extending to depths ranging from ~1.5 to 2 km, correlating with those reported in previous studies. Our results therefore contribute towards fundamental understanding of earthquake faulting as well as tectonic boundary and will be useful for hazard assessment and disaster mitigation.
Language: English
Topic: Seismic Waves and Analysis
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
Awards: Modeling of ambient noise wavefield for constructing 3D S-wave velocity structure and applications to urban areas, Geophysical imaging and monitoring of the subsurface structures using vibration of artificial structures, Estimation of S-wave velocity model around Kanto basin by using MeSO-net
OpenAlex ID: W4200535112