Identification of active faults and tectonic features through heat flow distribution in the Nankai Trough, Japan, based on high-resolution velocity-estimated bottom-simulating reflector depths

Earth, Planets and Space

Full Paper

Shuto Takenouchi¹  Kota Mukumoto¹  Takeshi Tsuji²  Kazuya Shiraishi³  Gou Fujie³  Shuichi Kodaira³  Yasuyuki Nakamura³ 

[1] Department of Earth Resources Engineering, Kyushu University, 744 Motooka Nishi-Ku, 819-0395, Fukuoka, Japan;Department of Earth Resources Engineering, Kyushu University, 744 Motooka Nishi-Ku, 819-0395, Fukuoka, Japan;School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, 113-8656, Tokyo, Japan;Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25 Showa-Machi, Kanazawa-Ku, 236-0001, Yokohama, Japan;

关键词: Bottom-simulating reflector (BSR);    Heat flow;    Active faults;    Plutonic rock;    Seismic reflection data;    Automated velocity analysis;    P-wave velocity;   

DOI  :  10.1186/s40623-023-01890-9

 received in 2022-10-14, accepted in 2023-08-26,  发布年份 2023

来源: Springer

【 摘 要 】

Estimates of heat flow can contribute to our understanding of geological structures in plate convergent zones that produce great earthquakes. We applied automated velocity analysis to obtain the accurate seismic profiles needed for precise heat flow estimates using six new seismic profiles acquired during R/V Kaimei KM18-10 voyage in 2018. We calculated heat flow values in the accretionary wedge of the Nankai Trough off the Kii Peninsula, Japan, from the positions of widespread bottom-simulating reflectors (BSRs) in seismic reflection profiles. Calculated conductive heat flow values from the depth of the BSR agree with previous studies where a regional trend is observed from ~ 50 mW/m2 to < 40 mW/m2 60 km landward from the deformation front. This trend is caused by thickening of accretionary sediments and the subduction of the Philippines Sea plate. Segments of profiles are marked by anomalous high heat flow values. Such anomalies represent alterations of the shallow crustal thermal structure caused either by a combination of topographic affects, surface erosion of the seafloor, or by fluid flow that transports heat by advection. We interpret heat flow anomalies (~ 100 mW/m2) as indicators of active faulting, which correspond to low seismic velocity zones along faults. Our results also showed relatively high heat flow at the landward end of several survey lines close to the Kii Peninsula, which we interpret to the possible presence of plutonic rocks that underlie the Kii Peninsula and extend offshore and may be the cause of geothermal springs, steep geothermal gradients, and high heat flow.Graphical abstract

【 授权许可】

CC BY   
© The Society of Geomagnetism and Earth, Planetary and Space Sciences / The Seismological Society of Japan / The Volcanological Society of Japan / The Geodetic Society of Japan / The Japanese Society for Planetary Sciences 2023

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