气候变化领域集成服务门户(CCPortal): High Fluid-Pressure Patches Beneath the Décollement: A Potential Source of Slow Earthquakes in the Nankai Trough off Cape Muroto

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DOI	10.1029/2021JB021831
	High Fluid-Pressure Patches Beneath the Décollement: A Potential Source of Slow Earthquakes in the Nankai Trough off Cape Muroto
	Hirose T.; Hamada Y.; Tanikawa W.; Kamiya N.; Yamamoto Y.; Tsuji T.; Kinoshita M.; Heuer V.B.; Inagaki F.; Morono Y.; Kubo Y.
发表日期	2021
ISSN	21699313
卷号	126 期号:6
英文摘要	Pore pressure plays a key role in the generation of earthquakes in subduction zones. However, quantitative constraints for its determination are quite limited. Here, we estimate the subsurface pore pressure by analyzing the transient upwelling flow of drilling mud from borehole C0023A of the International Ocean Discovery Program (IODP) Expedition 370, in the Nankai Trough off Cape Muroto. This upward flow provided the first direct evidence of an overpressured aquifer in the underthrust sediments off Cape Muroto. To estimate the pre-drilling pore pressure in the overpressured aquifer around a depth of 950–1,050 m below sea floor, we examined the measured porosities of core samples retrieved from nearby IODP wells; we then proceeded to explain the observed time evolution of the flow rate of the upwelling flow by modeling various sized aquifers through solving a radial diffusion equation. It was observed that for a permeability of 10−13 m2, the aquifer possessed an initial excess pore pressure of ∼5–10 MPa above the hydrostatic pressure, with a lateral dimension of several hundred meters and thickness of several tens of meters. The overpressure estimates from the porosity-depth profile at Site C0023 differ from those at other drill sites in the region, suggesting the possible existence of multiple overpressured aquifers with a patchy distribution in the underthrust sediments of the Nankai Trough. As pore pressure is relevant in maintaining fault stability, the overpressured aquifers may be the source of slow earthquakes that have been observed around the drilling site. © 2021. The Authors.
英文关键词	fluid pressure; Nankai Trough; slow earthquake
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187043
作者单位	Kochi Institute for Core Sample Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kochi, Japan; Graduate School of Engineering, Kyoto University, Kyoto, Japan; Department of Planetology, Graduate School of Science, Kobe University, Kobe, Japan; Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan; Earthquake Research Institute, University of Tokyo, Tokyo, Japan; MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany; Mantle Drilling Promotion Office, Institute for Marine-Earth Exploration and Engineering (MarE3), JAMSTEC, Yokohama, Japan
推荐引用方式 GB/T 7714	Hirose T.,Hamada Y.,Tanikawa W.,et al. High Fluid-Pressure Patches Beneath the Décollement: A Potential Source of Slow Earthquakes in the Nankai Trough off Cape Muroto[J],2021,126(6).
APA	Hirose T..,Hamada Y..,Tanikawa W..,Kamiya N..,Yamamoto Y..,...&Kubo Y..(2021).High Fluid-Pressure Patches Beneath the Décollement: A Potential Source of Slow Earthquakes in the Nankai Trough off Cape Muroto.Journal of Geophysical Research: Solid Earth,126(6).
MLA	Hirose T.,et al."High Fluid-Pressure Patches Beneath the Décollement: A Potential Source of Slow Earthquakes in the Nankai Trough off Cape Muroto".Journal of Geophysical Research: Solid Earth 126.6(2021).