3:30 PM - 4:30 PM
[J06-P-06] Estimating long-term and short-term slow slip events in the Bungo Channel area by MCMKF-based inversion.
We estimated space-time evolution of long-term and short-term slow slip events (L-SSE and S-SSE, respectively) in the Bungo Channel region between Jan. 1, 2009 and Dec. 31, 2012, 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, 2009 and Dec. 31, 2012 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 slip on the plate boundary at the Nankai Trough. 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. During this period, in addition to a L-SSE that occurred for about one year, S-SSEs have been inferred in the eastern Shikoku and western Kyushu. The inferred L-SSE is consistent with previous studies such as Yoshioka [2015], and the timing and location of S-SSE is similar to those estimated by Nishimura [2014]. This is the first case that space-time evolutions of both L-SSE and S-SSE have been estimated in the Bungo Channel region from a single inversion analysis. In the presentation we will show the results in detail and discuss the similarities and differences between L-SSE and S-SSE.