TY - JOUR
T1 - High-resolution 3-D S-velocity structure in the D″ region at the western margin of the Pacific LLSVP
T2 - Evidence for small-scale plumes and paleoslabs
AU - Suzuki, Yuki
AU - Kawai, Kenji
AU - Geller, Robert J.
AU - Tanaka, Satoru
AU - Siripunvaraporn, Weerachai
AU - Boonchaisuk, Songkhun
AU - Noisagool, Sutthipong
AU - Ishihara, Yasushi
AU - Kim, Taewoon
N1 - Funding Information:
This research was partly supported by grants from the Japanese Ministry of Education, Culture, Sports, Science and Technology (Nos. 16K05531, 15K17744, 15H05832, and 18K03797), Earthquake Research Institute of the University of Tokyo (ERI JURP 2016-F2-07, 2017-F2-07, 2018-F2-07) and a grant for Excellent Young Researchers at The University of Tokyo to K.K. The authors thank all the people in the TSAR project for installing and servicing the seismic array, especially Koji Miyakawa, Benjawut Piromfong, Keiichi Yokoyama and Ryohei Iritani. We thank the Editor, Prof. Vernon Cormier, and the two reviewers, Prof. Barbara Romanowicz and Prof. Mingming Li, for their detailed comments, which significantly improved the quality of this manuscript. We thank Dr. Daniel A. Frost, for his constructive comments. We thank Prof. Ed Garnero for the data on the location of the margin of the LLSVP and valuable discussions while conducting this research. We used a global tomography model (SEMUCB-WM1) data from the UC Berkeley Global Seismology group web page. The final models (shown in Fig. 3) can be downloaded from the Institutional Repository of the University of Tokyo (Suzuki et al. 2020). Some figures were made with GMT (http://gmt.soest.hawaii.edu). We thank the Incorporated Research Institutions for Seismology (IRIS) for making a large dataset of high-quality data available freely. We used waveform data from the following networks: Ocean Hemisphere Research Center (OHRC), Thai Seismic Monitoring Network (TM), Malaysian National Seismic Network (MY), Thai Seismic ARray (TSAR), Myanmar National Seismic Network (MM), New China Digital Seismograph Network (IC), Broadband Array in Taiwan for Seismology (TW) and Australian National Seismograph Network (AU). We thank the Computational Infrastructure for Geodynamics (http://geodynamics.org), which is funded by the NSF under awards EAR-0949446 and EAR-1550901, for providing SPECFEM3D_GLOBE 7.0.0 published under the GPL 2 license. For this study, we have used the computer systems of the Earthquake and Volcano Information Center of the Earthquake Research Institute, the University of Tokyo. This research was partially supported by Initiative on Promotion of Supercomputing for Young or Women Researchers, Information Technology Center, The University of Tokyo. All data needed to evaluate the conclusions in the paper are presented in the paper and/or the Supplementary materials. The seismic waveforms except observed at TSAR stations can be downloaded freely from the various data centers noted above. The TSAR data analyzed during the current study will become publicly available in spring 2021 in the Ocean Hemisphere Research Center (OHRC; network name is “Pacific21” and network code is “PS”), the Earthquake Research Institute (ERI), the University of Tokyo, which provides the full-SEED data through the Breq-Fast system, but access is limited to project team members until that time, due to the contractual arrangements under which the TSAR array was established. The daily plot images of three components are open at the OHRC site (http://ohpdmc.eri.u-tokyo.ac.jp/wave/qdaily3.TSAR.html). Additional data related to this paper may be requested from the authors.
Funding Information:
This research was partly supported by grants from the Japanese Ministry of Education, Culture, Sports, Science and Technology (Nos. 16K05531 , 15K17744 , 15H05832 , and 18K03797 ), Earthquake Research Institute of the University of Tokyo (ERI JURP 2016-F2-07 , 2017-F2-07 , 2018-F2-07 ) and a grant for Excellent Young Researchers at The University of Tokyo to K.K. The authors thank all the people in the TSAR project for installing and servicing the seismic array, especially Koji Miyakawa, Benjawut Piromfong, Keiichi Yokoyama and Ryohei Iritani. We thank the Editor, Prof. Vernon Cormier, and the two reviewers, Prof. Barbara Romanowicz and Prof. Mingming Li, for their detailed comments, which significantly improved the quality of this manuscript. We thank Dr. Daniel A. Frost, for his constructive comments. We thank Prof. Ed Garnero for the data on the location of the margin of the LLSVP and valuable discussions while conducting this research. We used a global tomography model (SEMUCB-WM1) data from the UC Berkeley Global Seismology group web page. The final models (shown in Fig. 3 ) can be downloaded from the Institutional Repository of the University of Tokyo ( Suzuki et al., 2020 ). Some figures were made with GMT ( http://gmt.soest.hawaii.edu ). We thank the Incorporated Research Institutions for Seismology (IRIS) for making a large dataset of high-quality data available freely. We used waveform data from the following networks: Ocean Hemisphere Research Center (OHRC), Thai Seismic Monitoring Network (TM), Malaysian National Seismic Network (MY), Thai Seismic ARray (TSAR), Myanmar National Seismic Network (MM), New China Digital Seismograph Network (IC), Broadband Array in Taiwan for Seismology (TW) and Australian National Seismograph Network (AU). We thank the Computational Infrastructure for Geodynamics ( http://geodynamics.org ), which is funded by the NSF under awards EAR-0949446 and EAR-1550901, for providing SPECFEM3D_GLOBE 7.0.0 published under the GPL 2 license. For this study, we have used the computer systems of the Earthquake and Volcano Information Center of the Earthquake Research Institute, the University of Tokyo. This research was partially supported by Initiative on Promotion of Supercomputing for Young or Women Researchers, Information Technology Center, The University of Tokyo .
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/10
Y1 - 2020/10
N2 - Although previous tomographic studies found a large low S-velocity province (LLSVP) in the lowermost mantle beneath the Pacific, due to a lack of resolution it was unclear whether the LLSVP consists of clusters of small-scale low-velocity anomalies or large-scale anomalies. We recently deployed a seismic-array in Thailand which provides a dataset with wide azimuthal coverage of the western Pacific LLSVP. We analyze the new dataset using waveform inversion, and find high-velocity anomalies extending vertically to a height of ~400 km above the core-mantle boundary (CMB) beneath the Philippine Sea and small-scale low-velocity patches with a diameter of ~300 km at the CMB beneath New Guinea. The locations of the high-velocity anomalies are consistent with the past Izanagi-plate subduction boundary, and the low-velocity anomalies can be interpreted as a small-scale plume cluster. Hence we conclude that vertical flow (upwelling plumes and downwelling of slabs) is dominant in the lowermost mantle beneath the western Pacific region.
AB - Although previous tomographic studies found a large low S-velocity province (LLSVP) in the lowermost mantle beneath the Pacific, due to a lack of resolution it was unclear whether the LLSVP consists of clusters of small-scale low-velocity anomalies or large-scale anomalies. We recently deployed a seismic-array in Thailand which provides a dataset with wide azimuthal coverage of the western Pacific LLSVP. We analyze the new dataset using waveform inversion, and find high-velocity anomalies extending vertically to a height of ~400 km above the core-mantle boundary (CMB) beneath the Philippine Sea and small-scale low-velocity patches with a diameter of ~300 km at the CMB beneath New Guinea. The locations of the high-velocity anomalies are consistent with the past Izanagi-plate subduction boundary, and the low-velocity anomalies can be interpreted as a small-scale plume cluster. Hence we conclude that vertical flow (upwelling plumes and downwelling of slabs) is dominant in the lowermost mantle beneath the western Pacific region.
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U2 - 10.1016/j.pepi.2020.106544
DO - 10.1016/j.pepi.2020.106544
M3 - Article
AN - SCOPUS:85088871014
SN - 0031-9201
VL - 307
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
M1 - 106544
ER -