Japan Geoscience Union Meeting 2016

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS34] The 2016 Kumamoto Earthquake and related crustal activities

Thu. May 26, 2016 3:30 PM - 4:45 PM Poster Hall (International Exhibition Hall HALL6)

5:15 PM - 6:30 PM

[MIS34-P48] Slip-partitioned surface ruptures for the Mw 7.0 2016 Kumamoto, Japan, earthquake

*Shinji Toda1, Heitaro Kaneda2, Shinsuke Okada1, Daisuke Ishimura3 (1.International Research Institute of Disaster Science, Tohoku University, 2.Graduate School of Science, Chiba University, 3.Tokyo Metropolitan University)

Keywords:active fault, surface rupture, slip partition

An ENE-trending ~30-km-long significant surface ruptures emerged along the previously mapped Futagawa and northern Hinagu fault zones at the Mw 7.0 2016 Kumamoto earthquake (Kumahara et al., 2016, in this JpGU meeting). The rupture zone is mostly composed of right-lateral slip fault sections that has max. 2 m coseismic slip. But we also found ~6-km-long normal faulting rupture zone on the western foothill of Mt. Tawarayama, parallel to the right-lateral fault zone. The maximum amount of throw on the normal fault is about 2 m, which is equivalent to the one on the strike-slip fault. We suppose the simultaneous dip-slip and strike-slip motion on parallel faults occurred during the slip partitioning process near the surface from an NW-dipping oblique slip at seismogenic depth. The slip partitioning section may also correspond to the section relatively fewer aftershocks have been occurring. Understanding the slip partition on parallel faults leads to the proper fault grouping and identifying seismogenic fault zone.