HR: 1340h
AN: MR23B-0056    [Abstracts]
TI: Array Methods Used to Investigate D'' Structure Beneath South-East Asia Using P and S Waves
AU: * Chaloner, J
EM: j.chaloner@liverpool.ac.uk
AF: Department of Earth and Ocean Sciences, University of Liverpool, 4 Brownlow Street, , Liverpool, L69 3GP United Kingdom
AU: Thomas, C
EM: tine@liverpool.ac.uk
AF: Department of Earth and Ocean Sciences, University of Liverpool, 4 Brownlow Street, , Liverpool, L69 3GP United Kingdom
AU: Rietbrock, A
EM: a.rietbrock@liverpool.ac.uk
AF: Department of Earth and Ocean Sciences, University of Liverpool, 4 Brownlow Street, , Liverpool, L69 3GP United Kingdom
AB: A simplified migration method is used to investigate D'' structure under the Gulf of Tonkin off the coast of Vietnam, using earthquakes in the Philippines recorded at the KNET and GHENGIS arrays in the Tien-Shan region. 10 earthquakes are recorded at between 5 and 15 stations. These earthquakes have bounce points at the core-mantle boundary (CMB) covering a lateral extent of 3 degrees. We find evidence for the presence of a reflector in D'' with height varying between 290 and 110 km above the CMB. We interpret this as a discontinuity in P and S-wave velocities. The discontinuity appears to form a synclinal structure with an axis of folding oriented north-west to south-east. The apparent height of the discontinuity above the CMB is the same for both P and S-waves. In addition, in those areas where this discontinuity is furthest from the CMB, we find a second reflector of opposite polarity between 60 and 100 km above the CMB. This suggests that the velocity discontinuities may be the result of a double crossing of the post-perovskite phase boundary. Synthetic seismograms, produced using the reflectivity method, are used to test the robustness of the processing method and demonstrate that it is relatively insensitive to variations in the background 1D velocity model used to perform the migration.
DE: 3919 Equations of state
DE: 7207 Core (1212, 1213, 8124)
DE: 7208 Mantle (1212, 1213, 8124)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005