Upper Mantle Tomography in the Northwestern Pacific Region Using Triplicated P Waveforms

Nozomu Takeuchi1, Hitoshi Kawakatsu1, Satoru Tanaka2, Masayuki Obayashi2, Yongshun John Chen3, Jieyuan Ning4, Stephen P Grand5, Fenglin Niu6, James Ni7, Ryohei Iritani8, Koki K I Idehara9 and Takashi Tonegawa10, (1)Earthquake Research Institute, The University of Tokyo, Tokyo, Japan, (2)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (3)Southern University of Science and Technology, Department of Ocean Science and Engineering, Shenzhen, China, (4)Peking University, Beijing, China, (5)University of Texas, Austin, United States, (6)University of Science and Technology of China, School of Earth & Space Sciences, Anhui, China, (7)New Mexico State University Main Campus, Las Cruces, NM, United States, (8)Earthquake Research Institute, The University of Tokyo, Yayoi, Japan, (9)Earthquake Research Institute, University of Tokyo, Yayoi, Japan, (10)JAMSTEC, Yokosuka, Japan
Abstract:
We conducted delay time tomography of the upper mantle beneath the northwestern Pacific using P data from NECESSArray (NorthEast China Extended SeiSmic Array), F-net, and nearby available stations. To improve resolution and accuracy in the vicinity of mantle discontinuities, we extracted traveltimes of both initial and secondary phases observed at triplication distances by using a waveform fitting technique. Compared with the model obtained by using only the initial phase, the resolution just above the 410 km discontinuity is especially improved, and low-velocity anomalies beneath the Changbai volcano are clearly observed down to the 410 km discontinuity. Compared with previous models [Tang et al., 2014, Nature Geosci.; Obayashi et al., 2011, AGU Fall Meeting], low-velocity anomalies atop the 410 are more pronounced. The results of this study together with the previous receiver function analysis [Liu et al., submitted to EPSL] provide further support that we have hot material beneath the Changbai volcano.
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