Details

Autor(en) / Beteiligte

• Kimura, Haruo
• Tsutsumi, Hiroyuki
• Inari, Ayane
• Taniguchi, Kaoru
• Nakanishi, Toshimichi

Titel

Left-laterally deformed near-surface structures on the Tanna fault at Tashiro site, central Japan, revealed by ground penetrating radar profiling

Ist Teil von

• The Quaternary Research (Daiyonki-Kenkyu), 2024/05/01, Vol.63(2), pp.65-75

Ort / Verlag

Japan Association for Quaternary Research

Erscheinungsjahr

2024

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• Generally, we can estimate the strike-slip displacement of an active fault by detecting the lateral offset of fault-related deformed geomorphic features. However, when the geomorphic features are buried underground due to sedimentation or artificial filling, it is necessary to investigate the subsurface by drilling, trenching excavation, and geophysical exploration. In this study, we attempted to detect buried laterally deformed structures by ground penetrating radar (GPR) profiling, one of the geophysical survey methods to image the near-surface geological structures, at the Tashiro site on the Tanna fault. The GPR survey consists of 41 lines parallel to the fault trace with 40 m length and 0.5 m inline spacing. The GPR data were collected by common-offset modes using 50 MHz GPR systems (pulseEKKO PRO made by Sensors and Software Inc., Canada), and the horizontal scan-point interval was 0.5 m. Furthermore, we carried out wide-angle measurements and acquired common mid-point ensembles to estimate the electromagnetic wave velocity to process the depth conversion of the GPR sections. The results show a north-dipping band structure in the shallow part (less than 2 m depth) and a buried paleochannel structure in the deep part (more than 2 m depth). Both structures show left-lateral deformation, with the deeper structure, which was formed at an older age, being more strongly deformed. Thus, this study demonstrates that the GPR survey effectively detects the lateral offsets caused by active faults and confirms their cumulation.