[J03-P] Poster

[J03-P-02] Analysis of Detailed Crustal Strains due to the Dense GNSS Array in the Tokai Region, Central Japan

^○Teruyuki Kato¹, Hiromu Sakaue², Takuya Nishimura³, Ryoya Ikuta⁴, Yasushi Harada⁵ (1.Earthquake Research Institute, the University of Tokyo, Tokyo, Japan, 2.Graduate School of Science, Kyoto University, Kyoto, Japan, 3.Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan, 4.Institute of Geosciences, Faculty of Science, Shizuoka University, Shizuoka, Japan, 5.School of Marine Science and Technology, Tokai University, Shizuoka, Japan)

The Tokai region is an area of scientific interest where the Philippine Sea plate subducts from the eastern end of the Suruga-Nankai Trough in the south of the Japanese Islands, and is expected to generate a large interplate earthquake in the near future. Recent investigations suggest that the largest possible earthquake in this region could be M9 class earthquake, and is called as the Nankai Trough earthquake. Moreover, the area has experienced long-term slow slip events (SSE) during 2000-2005 and since around 2013. The Japanese University Consortium for GNSS Research (JUNCO) established a dense GNSS array in the region and started observation in around 2004 for monitoring the crustal deformation. The array is an augmentation of the GEONET, the nationwide GNSS array established by the Geospatial Information Authority of Japan (GSI). The network consists of more than 50 GNSS sites and is denser with 5-10km baseline lengths, compared with the 20km spacing of GEONET.
The data taken by the network has been used to monitor the strain accumulation in the area as well as to investigate slip evolution of the long-term SSE. This study shows temporal change of strains for the observed 12 years up until 2016. Results show strong disturbances from nearby large earthquakes of the 2009 August Suruga Bay earthquake (Mw6.3), and the 2011 Off Tohoku earthquake (Mw9.1). In particular, the Suruga Bay earthquake affected the area with significantly complicated strain pattern, suggesting importance of dense GNSS array introduced in this study. We are now archiving the obtained data together with ancillary data for making the data available more publicly for further researches in the area.