[J06-P] Poster

[J06-P-07] A trial to find long-term variation in slip-deficits in the Bungo Channel region, Nankai Trough

^○Shinichi Miyazaki¹, Takatoshi Yokoi¹, Hiromu Sakaue¹, Jun'ichi Fukuda² (1.Kyoto University, Kyoto, Japan, 2.ERI, The University of Tokyo, Tokyo, Japan)

We estimated space-time variation of secular slip and slip-deficits in the Bungo Channel region between two successive long-term slow slip events (L-SSEs) by employing the Monte Carlo Mixture Kalman Filter (MCMKF)-based Network Inversion Filter (NIF) [Fukuda et al.,2014]. We use GNSS time series at GEONET stations between Jan. 1, 2012 and Dec. 31, 2015 as provided by Takuya Nishimura [Personal Communication]. First we have pre-processed the original GNSS time series to remove secular velocities, annual and semi-annual variations, offsets associated with earthquakes and antenna changes and postseismic deformations. Then those pre-processed time series would contain only transient deformation and local benchmark wobble provided there is no other noise source. We inverted pre-processed GNSS time series to estimate transient slips, if any, and slip-deficits on the plate boundary at the Nankai Trough. Following Yokoi et al. [2017, this meeting], we employ plate configuration data by Hirose et al. [2008] and select the area of about 200km long to the east and 280km long to the north as the model region. We subdivide the model region into 719 subfault patches, and expand the slip by a series of 24 spatial depleted basis functions. Up to now only short-term slow slip events (S-SSEs) have been found, and long-term variation of slip deficits are within uncertainties.