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Metastable olivine wedge beneath the Japan Sea imaged by seismic interferometry

Shen, Zhichao and Zhan, Zhongwen (2020) Metastable olivine wedge beneath the Japan Sea imaged by seismic interferometry. Geophysical Research Letters, 47 (6). Art. No. e2019GL085665. ISSN 0094-8276. https://resolver.caltech.edu/CaltechAUTHORS:20191220-095143786

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Abstract

The metastable olivine wedge (MOW) within subducted slabs has long been hypothesized to host deep‐focus earthquakes (>300 km). Its presence would also rule out hydrous slabs being subducted into the mantle transition zone. However, the existence and dimensions of MOW remain debatable. Here, we apply inter‐source interferometry, which converts deep earthquakes into virtual seismometers, to detect the seismic signature of MOW without influence from shallow heterogeneities. With data from the Hi‐net, we confirm the existence of MOW beneath the Japan Sea and constrain its geometry to be ~30 km thick at 410‐km depth and gradually thinning to a depth of 580 km at least. Our result supports transformational faulting of metastable olivine as the initiation mechanism of deep earthquakes, although large events (M7.0+) probably rupture beyond the wedge. Furthermore, the slab core must be dehydrated at shallower depth and only transports negligible amount of water into the transition zone.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019GL085665DOIArticle
https://doi.org/10.31223/osf.io/d5r6tDOIDiscussion Paper
https://osf.io/mxr87Related ItemSupplemental Materials
ORCID:
AuthorORCID
Shen, Zhichao0000-0003-0458-5264
Zhan, Zhongwen0000-0002-5586-2607
Additional Information:© 2020 American Geophysical Union. Received 6 OCT 2019; Accepted 26 FEB 2020; Accepted article online 29 FEB 2020. We are grateful to Micheal Gurnis, Paul Asimow, Sidao Ni, and Wenbo Wu for discussions and suggestions. We are also grateful for reviews from two anonymous reviewers, which helped to improve the manuscript. Seismic data are collected from the Data Management Center of the Incorporated Research Institutions for Seismology (https://www.iris.edu/dms/nodes/dmc), Hi‐net (http://www.hinet.bosai.go.jp/) and F‐net (http://www.fnet.bosai.go.jp/). The earthquake catalog and focal mechanisms are downloaded from ISC‐EHB distributed by the International Seismological Centre (ISC, http://www.isc.ac.uk/) and National Research Institute for Earth Science and Disaster Resilience (NIED, http://www.fnet.bosai.go.jp/event/search.php?LANG=en). The earthquake arrival time data is available at the Japan Meteorological Agency (JMA, http://www.data.jma.go.jp/svd/eqev/data/bulletin/index_e.html).
Group:Seismological Laboratory
Subject Keywords:metastable olivine; inter‐source interferometry; deep earthquake mechanism; dry slab core; mantle transition zone
Issue or Number:6
Record Number:CaltechAUTHORS:20191220-095143786
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191220-095143786
Official Citation:Shen, Z., & Zhan, Z. (2020). Metastable olivine wedge beneath the Japan Sea imaged by seismic interferometry. Geophysical Research Letters, 47, e2019GL085665. https://doi.org/10.1029/2019GL085665
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100387
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Dec 2019 19:44
Last Modified:08 Apr 2020 16:59

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