气候变化领域集成服务门户(CCPortal): Three-Dimensional P Wave Velocity Structure of the Northern Hikurangi Margin From the NZ3D Experiment: Evidence for Fault-Bound Anisotropy

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DOI	10.1029/2020JB020433
	Three-Dimensional P Wave Velocity Structure of the Northern Hikurangi Margin From the NZ3D Experiment: Evidence for Fault-Bound Anisotropy
	Arai R.; Kodaira S.; Henrys S.; Bangs N.; Obana K.; Fujie G.; Miura S.; Barker D.; Bassett D.; Bell R.; Mochizuki K.; Kellett R.; Stucker V.; Fry B.; NZ3D Team
发表日期	2020
ISSN	21699313
卷号	125 期号:12
英文摘要	We present a high-resolution three-dimensional (3-D) anisotropic P wave velocity (Vp) model in the northern Hikurangi margin offshore Gisborne, New Zealand, constructed by tomographic inversion of over 430,000 first arrivals recorded by a dense grid of ocean bottom seismometers. Since the study area covers a region where shallow slow slip events (SSEs) occur repeatedly and the subduction of a seamount is proposed, it offers an ideal location to link our understanding of structural and hydrogeologic properties at megathrust faults to slip behavior. The Vp model reveals an ~30-km-wide, low-velocity accretionary wedge at the toe of the overriding plate, where previous seismic reflection studies show a series of active thrust faults branching from the plate interface. We find some locations with significant Vp azimuthal anisotropy >5% near the branching faults and the deformation front. This finding suggests that the anisotropy is not ubiquitous and homogeneous within the overriding plate, but more localized in the vicinity of active thrust faults. The fast axes of Vp within the accretionary wedge are mostly oriented to the plate convergence direction, which is interpreted as preferentially oriented cracks in a compressional stress regime associated with plate subduction. We find that the magnitudes of anisotropy are roughly equivalent to values found at oceanic spreading centers, where the extensional stress regime is dominant and the crack density is expected to be higher than subduction zones. This consideration may indicate that additional effects such as fault foliation and clay mineral alignment also contribute to upper plate anisotropy along subduction margins. ©2020. The Authors.
英文关键词	inverted IC discharges; isolated breakdown process; negative cloud-to-ground flash; strong lower positive charge region
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/187455
作者单位	Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan; GNS Science, Lower Hutt, New Zealand; Institute for Geophysics, University of Texas at Austin, Austin, TX, United States; Imperial College London, London, United Kingdom; Earthquake Research Institute, University of Tokyo, Tokyo, Japan
推荐引用方式 GB/T 7714	Arai R.,Kodaira S.,Henrys S.,et al. Three-Dimensional P Wave Velocity Structure of the Northern Hikurangi Margin From the NZ3D Experiment: Evidence for Fault-Bound Anisotropy[J],2020,125(12).
APA	Arai R..,Kodaira S..,Henrys S..,Bangs N..,Obana K..,...&NZ3D Team.(2020).Three-Dimensional P Wave Velocity Structure of the Northern Hikurangi Margin From the NZ3D Experiment: Evidence for Fault-Bound Anisotropy.Journal of Geophysical Research: Solid Earth,125(12).
MLA	Arai R.,et al."Three-Dimensional P Wave Velocity Structure of the Northern Hikurangi Margin From the NZ3D Experiment: Evidence for Fault-Bound Anisotropy".Journal of Geophysical Research: Solid Earth 125.12(2020).