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

Monday, 15 December 2014: 4:45 PM
Nozomu Takeuchi1, Hitoshi Kawakatsu2, Satoru Tanaka3, Masayuki Obayashi3, Yongshun John Chen4, Jieyuan Ning4, Stephen P Grand5, Fenglin Niu6, James Ni7, Ryohei Iritani1, Koki K I Idehara1 and Takashi Tonegawa3, (1)Earthquake Research Institute, University of Tokyo, Yayoi, Japan, (2)Earthquake Research Institute, University of Tokyo, Tokyo, Japan, (3)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (4)Peking University, Beijing, China, (5)University of Texas, Austin, TX, United States, (6)Rice University, Houston, TX, United States, (7)New Mexico State University Main Campus, Las Cruces, NM, United States
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.