Influence of crustal lithology and the thermal state on microseismicity in the Wakayama region, southern Honshu, Japan

Earth, Planets and Space

Makoto Otsubo¹  Toru Matsuzawa²  Shinji Toda³  Sumire Maeda⁴  Takumi Matsumoto⁴ 

[1] Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 7;Graduate School of Science, Tohoku University;International Research Institute of Disaster Science, Tohoku University;National Research Institute for Earth Science and Disaster Resilience;

关键词: Lithological heterogeneity;    Seismicity;    Seismogenic depth;    Lithospheric thermal structure;    Geological structure;    Kii Peninsula;   

DOI  :  10.1186/s40623-021-01503-3

来源: DOAJ

【 摘 要 】

Abstract Here we investigate the influence of the lithology and thermal state of the upper crust on earthquake distributions beneath the Wakayama region, southern Honshu, Japan, to better understand the influence of crustal conditions on regional seismogenesis. The earthquakes are concentrated in the deeper sections of mafic belts and shallower sections of pelitic belts, based on a comparison of relocated hypocenters and estimated subsurface geological structures. We compare the frictional properties of pelitic rocks and basalt, as obtained from petrological experiments, with the hypocenter depth distributions in pelitic and mafic belts to assess the control of crustal lithology on the depth extent of regional seismicity. The earthquake distributions are consistent with the temperature ranges over which the respective rock types are expected to exhibit a velocity-weakening behavior, based on the petrological experiments. The results suggest that the occurrence of shallow intraplate earthquakes is controlled by the temperature- and lithology-dependent friction of the upper crust.

【 授权许可】

Unknown