[SSS15-P11] Application a trans-dimensional inversion to slip-deficit rate estimation along Nankai Trough
Keywords:Trans-dimensional inversion, slip-deficit rate, Nankai Trough
We use displacement rates at GEONET stations in southwest Japan from March 2005 to February 2011, which was provided by Noda et al. (2017, SSJ). To obtain a slip-deficit rate distribution from the geodetic data, we employ a trans-dimensional source inversion methodology suggested by Kubo et al. (2017, JpGU). In this methodology, the spatial distribution of slip-deficit rates is modeled by a variable number of Voronoi cells. Unknown parameters are the number of Voronoi cells, the locations of Voronoi cells, and values of slip-deficit rate at Voronoi cells. To obtain the posterior distribution of the unknown parameters, we employ the reversible jump Markov chain Monte Carlo method (e.g., Green 1995) using the parallel tempering algorithm (e.g., Sambridge 2013). An assumed geometric model of the upper interface of the Philippine Sea plate is based on CAMP Standard Model Version 1.0 (Hashimoto et al., 2004) and is divided into several subfaults. A rake angle at each subfault is set so that the slip direction is consistent with the subduction direction (e.g., Sella et al. 2003). For Green’s functions, we adopt the concept of back-slip proposed by Savage (1983), and calculate the theoretical static displacements caused by a unit slip on each subfault assuming a homogeneous elastic half-space (Okada 1992).
The preliminary results show that a zone with high slip-deficit rate is found in the coastal region along the Nankai Trough.