Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Poster

S (Solid Earth Sciences) » S-SS Seismology

[S-SS10] Seismic wave propagation: Theory and Application

Thu. May 24, 2018 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Kiwamu Nishida(Earthquake Research Institute, University of Tokyo), Kazuya Shiraishi(Japan Agency for Marine-Earth Science and Technology), Takao Nibe((株)地球科学総合研究所, 共同), Kaoru Sawazaki(National Research Institute for Earth Science and Disaster Resilience)

[SSS10-P11] The Study on Rupture Directivity of the 2016 Meinong Earthquake using Back-projection Method

*Chun Hao Hsu1, Strong Wen1, Chau-Huei Chen1 (1.Institute of Seismology, National Chung-Cheng University Minhsiung, Chiayi, Taiwan)

Keywords:Back-projection, The 2016 Meinong earthquake, rupture directivity

A ML 6.6 seismic event was occurred on 6 February 2016 with a maximum intensity 7 in the Meinong area, Taiwan. However, the main damage area of the earthquake was not located in Meinong source area, but caused serious destroyed in Tainan area where is located at the west side of the epicenter. The disaster is the most serious in Taiwan after the 921 Chi-Chi earthquake. Such serious disaster may be caused by the source rupture directivity effect. The focal mechanism of the earthquake reveals strike-slip faulting and contains reverse component. In this study, we applied the S-wave waveform envelope data which was recorded by 12 strong motion stations with the epicentral distances are between 25 and 50 km around the source area. We obtained the more accurated travel time of S-wave by using pseudo-bending method under the 3-D velocity model. Thus, the seismic source spatiotemporal evolution was obtained by using the back-projection method. In our results, the high-frequency (HF) energy is located at about 10 km east-part of the epicenter in the rupture initiation. The HF energy propagated northwestward, and about 5 seconds later, the HF energy propagated westward. According to this results, these might suggest a westward rupture. The HF energy is transmitted from the epicenter of the Meinong area to the western coastal plain area, creating constructive interference in the plains of soft sediments and causing huge damage to Tainan area. This phenomenon reflects that the main disaster area is not always occurred around the source area.