Ambient noise tomography for a high-resolution 3D S-wave velocity model of the Kinki Region, Southwestern Japan, using dense seismic array data

Abstract

Research interest in the Kinki region, southwestern Japan, has been aroused by the frequent occurrence of microearthquake activity that do not always coincide with documented active fault locations. Previous studies in the Kinki region 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. From the cross-correlation of the vertical components of the ambient seismic noise data recorded by a densely distributed seismic array, we estimated Rayleigh wave phase velocities using a frequency domain method. Then, we applied a direct surface wave tomographic method for the measured phase velocity dispersion data to obtain a 3D S-wave velocity model of the Kinki region. 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. 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. Graphical abstract

Ambient Noise Tomography Reveals Asymmetric Impact Damage Zone Beneath Lonar Crater, India: Implications for Oblique Impact Cratering in Heterogeneous Basalt, With Planetary Applications

“…Ambient Noise Tomography (ANT) is an excellent seismological technique that can be used for imaging shallow sub-surface of planetary bodies where occurrences of quakes are infrequent (e.g., Shapiro & Campillo, 2004;Shapiro et al, 2005). It provides a high-resolution 3D shear wave velocity (V S ) image of the planetary upper crust up to a few hundred meters depth (Chen et al, 2021;Mordret et al, 2014Mordret et al, , 2019, and in some cases, it could be up to a few 10 km deep (Lin et al, 2007;Nthaba et al, 2022;Yao et al, 2006). Hence, this technique is useful for imaging the subsurface of impact craters.…”

Blast-Assisted Subsurface Characterisation Using a Novel Distributed Acoustic Sensing Setup Based on Geometric Phases

“…Surface waves may be artificially induced at specific frequencies and amplitudes using special sources like vibrating trucks or blasts. Several studies show subsurface characterisation using dense geophone arrays whose spatial resolution is at minimum of around 50 to 60 m [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The limited density of these arrays as well as the installation cost and difficulty may be a challenge, especially in hard-to-reach areas like the ocean bottom or densely populated urban areas [ 9 ].…”