Imperial College London
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DrRebeccaBell

Faculty of Engineering, Department of Earth Science & Engineering

Reader in Tectonics
 
 
 
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Contact

 

+44 (0)20 7594 0903rebecca.bell

 
 
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Location

 

2.37aRoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Arai:2020:10.1029/2020jb020433,
author = {Arai, R and Kodaira, S and Henrys, S and Bangs, N and Obana, K and Fujie, G and Miura, S and Barker, D and Bassett, D and Bell, R and Mochizuki, K and Kellett, R and Stucker, V and Fry, B},
doi = {10.1029/2020jb020433},
journal = {Journal of Geophysical Research: Solid Earth},
pages = {1--20},
title = {Threedimensional P wave velocity structure of the Northern Hikurangi margin from the NZ3D experiment: evidence for faultbound anisotropy},
url = {http://dx.doi.org/10.1029/2020jb020433},
volume = {125},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We present a highresolution threedimensional (3D) 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 ~30kmwide, lowvelocity 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.
AU  - Arai,R
AU  - Kodaira,S
AU  - Henrys,S
AU  - Bangs,N
AU  - Obana,K
AU  - Fujie,G
AU  - Miura,S
AU  - Barker,D
AU  - Bassett,D
AU  - Bell,R
AU  - Mochizuki,K
AU  - Kellett,R
AU  - Stucker,V
AU  - Fry,B
DO  - 10.1029/2020jb020433
EP  - 20
PY  - 2020///
SN  - 2169-9313
SP  - 1
TI  - Threedimensional P wave velocity structure of the Northern Hikurangi margin from the NZ3D experiment: evidence for faultbound anisotropy
T2  - Journal of Geophysical Research: Solid Earth
UR  - http://dx.doi.org/10.1029/2020jb020433
UR  - https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JB020433
UR  - http://hdl.handle.net/10044/1/87280
VL  - 125
ER  -
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