HR: 0800h
AN: G21C-0671    [Abstracts]
TI: Modeling of Crustal Deformation in SW Japan using GPS Data -Simultaneous Estimation of Interplate Coupling and Block Rotation-
AU: * MIYAO, K
EM: miyao@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki 6-6, Aobaku, Sendai, 980-8578, Japan
AU: MIURA, S
EM: miura@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki 6-6, Aobaku, Sendai, 980-8578, Japan
AU: OHTA, Y
EM: ohta@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki 6-6, Aobaku, Sendai, 980-8578, Japan
AU: WALLACE, L
EM: L.Wallace@gns.cri.nz
AF: Institute of Geological and Nuclear Sciences, 1 Fairway Drive, Avalon, Lower Hutt, 5010, New Zealand
AU: NAKAO, S
EM: nakao@sci.kagoshima-u.ac.jp
AF: Faculty of Science, Kagoshima University, 1-21-24, Korimoto, Kagoshima, 890-8580, Japan
AU: HASEGAWA, A
EM: hasegawa@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki 6-6, Aobaku, Sendai, 980-8578, Japan
AB: We applied a new method devised by McCaffery [2002] to estimate both slip deficit and block rotation simultaneously to SW Japan where the tectonics is complex and the crustal deformation is not uniform. We estimated the distribution of the slip deficit on the subducting Philippine Sea Plate and other assumed block boundaries in SW Japan together with block rotation parameters simultaneously. As a result we can clarify the along-arc variation of the slip deficit on subduction zone, and relative block motion derived from block rotation. We assume some geological faults, grabens and linearly-aligned hypocenters as block boundaries. We also considered the Okinawa micro-plate (ON) proposed by Bird [2003]. The data used in the analysis is the GPS site velocities obtained from GEONET. The results show the larger slip deficit of the subducting slab in the northern Hyuga-nada and off Shikoku, while smaller in the southern Hyuga-nada. The coupling across the Median Tectonic Line (MTL) and Beppu-Shimabara Graben is very shallow (~10km depth), however, Amurian plate (AM) and Mid-Kyushu block (MK) couple strongly across the other part inland Kyushu on the contrary. The Euler poles of AM-ON and AM-MK are located at long. 133°E, and lat. 29°N with an angular velocity of 3.1°/Ma and at long. 126°E, and lat. 40°N with 0.5°/Ma, respectively. The AM-ON angular velocity obtained in this study is about 1/5 of that estimated by Kodama [1995] and shows fair agreement. It is necessary to perform more detailed analyses by adding more data from the Nansei Islands and Shikoku area. The long-term relative motions between adjacent blocks are also estimated. The result shows grabens inland Kyushu are opening, the blocks across the MTL are moving right-laterally, and the MK and the southernmost Kyushu blocks are also moving right-laterally in long term.
DE: 0726 Ice sheets
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 7209 Earthquake dynamics (1242)
DE: 8158 Plate motions: present and recent (3040)
SC: Geodesy [G]
MN: 2007 Fall Meeting