[SSS10-P18] Horizontal Crusatl Strain in Southwest Japan:Attempt to extract local deformation using a Kriging method
Keywords:Crustal deformation, Southwest Japan, Strain, Local deformation, Kriging method, GPS
We use horizontal displacement rates derived from GEONET final coordinate time series at 569 sites from Kyushu to Kinki districts during the period of 2006-2009. Regardless of the strain analysis method, the southern part of Shikoku region has been shortened at a rate of 0.15-0.30 ppm/yr in the NW-SE direction due to the PHS convergence. The direction of the compression axis rotates counterclockwise from western Shikoku to southern Kyushu, which implies PHS convergence becomes less effective. Similarly strain rates decrease rapidly with increasing distance from the Nankai Trough. Comparing strain rate fields from two different methods, the Kriging is more sensitive to a local disturbance. However, systematic local deformation affected by active faults and geological structure are not clear though we have expected it around MTL and other tectonic lines. Spatial resolution of original GEONET data may be insufficient to extract local disturbance since its average station separation is 15-20 km. In this sense dense campaign measurements for a specific target will play an important role when it is linked to GEONET.