[SCG48-P14] Spatial distribution of the electrical resistivity beneath western part of Shikoku Island where long-term SSE events have repeatedly occurred
Keywords:slow slip event beneath the Bungo Channel, 3-D resistivity structure, Network-MT observation
Conductive portions are commonly detected in the mid-crust of the target region. Their roots are just on the upper surface of the subducting Philippine Sea slab. This may suggest dehydration there. Among the spatial distribution of resistivity, that of seismic P-wave attenuation (Kita and Matsubara, 2016), and that of SSE slips (e.g. Ozawa et al., 2013, Yoshioka et al., 2015, Hirose et al., 2018), some mutually related features are detected. Low Qp (high attenuation) areas tend to correspond to highly conductive areas. The low Qp and highly conductive area are detected just above the subducting slab and outside of the SSE area. Inside the SSE area, while Qp takes generally high values, a patchy conductive area is detected in overall resistive background structure.
This study is supported by JSPS KAKENHI Grand Number JP16H06475 in Scientific Research on Innovative Areas "Science of Slow Earthquakes". It is also partly supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its Earthquake and Volcano Hazards Observation and Research Program. We acknowledge staffs of the Nippon Telegraph and Telephone WEST Corporation for their cordial support in the survey. We also thank H. Abe, A. Takeuchi and Y. Suwa for their help in preparing and installing instruments.