HR: 0830h
AN: S11E-0355    [PDF]
TI: Seismic Evidence for Slab Melting from Strong Scattering Waves
AU: * Lin, C
EM: lin@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, P O Box 1-55, Nankang, Taipei, 115 Taiwan
AU: Ando, M
EM: ando@seis.nagoya-u.ac.jp
AF: Recearch Center for Seismology and Volcanology, Nagoya University, Chikusa, Nagoya, 464-8602 Japan
AU: Fujii, N
AF: Recearch Center for Seismology and Volcanology, Nagoya University, Chikusa, Nagoya, 464-8602 Japan
AU: Yamaoka, K
AF: Recearch Center for Seismology and Volcanology, Nagoya University, Chikusa, Nagoya, 464-8602 Japan
AU: Tadokoro, K
AF: Recearch Center for Seismology and Volcanology, Nagoya University, Chikusa, Nagoya, 464-8602 Japan
AU: Jin, A
AF: National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Ibaraki, 305-0006 Japan
AU: Obara, K
AF: National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Ibaraki, 305-0006 Japan
AU: Ishida, M
AF: National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Ibaraki, 305-0006 Japan
AB: Slab melting in some young and hot subduction zones has been reported from geochemical observations and thermal modeling, but there was still no seismic evidence to confirm it. Also the detailed geometry in the deep part of the melting slab is often ambiguous in that the intraslab earthquakes within the Wadati-Benioff zone are only limited to shallower depths. To improve the understanding of both the seismic features and the geometry found in a young and hot subducted slab, we analyze an anomalous moonquake-like seismogram that was generated by an intermediate-depth earthquake recorded in central Japan. Since the subducted Philippine Sea plate in central Japan is extremely young (0-2 Ma) and therefore hot, strong partial melting might have taken place to produce abundant melting spots in the subducted slab. Melting spots, identified as ­bright spot­", could efficiently reflect or scatter much seismic energy and then generate many later phases with large amplitudes. As a result, slab melting can be identified in the deep bending part of the subducted Philippine Sea plate from strong seismic scattering.
DE: 7218 Lithosphere and upper mantle
DE: 7230 Seismicity and seismotectonics
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8123 Dynamics, seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting