Crustal deformation associated with M8.1 earthquake in Solomon Islands

Yousuke Miyagi(1), Taku Ozawa(2) and Masanobu Shimada(1)

(1) Japan Aerospace Exploration Agency, Tsukuba Space Center, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan
(2) National Research Institute for Earth Science, and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan


On April 1, 2007 (UTC), an M8.1 interplate earthquake occurred off the Solomon Islands, where is the subduction zone between the Pacific Plate and the Australian Plate (S8.48°, E156.98°). This earthquake was accompanied by a large tsunami and caused considerable damage in the area. The Japan Aerospace Exploration Agency (JAXA) performed emergency observation using the Advanced Land Observing Satellite (ALOS) and tried to acquire information on the afflicted area as soon as possible. A remote-sensing technique has the advantage of being able to observe and monitor a disaster that has occurred in a remote location like the Solomon Islands that is difficult to access and receives few geophysical observations. PALSAR data can be applied in Differential Interferometric SAR (DInSAR) techniques to detect precise ground deformation, and such precise geodetic data is helpful for inferring a fault model. In the research for such a megathrust earthquake in remote location, seismic data has so far been mainly used for a seismic fault modeling. In this presentation, however, we jointly use the geodetic data detected by PALSAR/DInSAR data and field investigation [Nishimura et al., 2008] for estimating a slip distribution of the fault. The estimated slip distribution exhibits good agreement with that deduced from the teleseismic data [Yagi, 2007], in which they had a two-eyed large slip area around the hypocenter and northwest of it, and a calculated interferogram using our model well explains the observed deformation.



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