Seismic velocity structure in the source region of the 2016 Kumamoto earthquake sequence, Japan
| Autor: | Hiroshi Shimizu, Tomomi Okada, Makoto Okubo, Shin'ichi Sakai, Masahiro Kosuga, Hiroaki Takahashi, Youichi Asano, Azusa Shito, Satoshi Matsumoto, Masayuki Yoshimi, Hiroki Miyamachi, Yuta Maeda, Takahiro Ohkura |
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| Rok vydání: | 2017 |
| Předmět: |
010504 meteorology & atmospheric sciences
Crust Induced seismicity 010502 geochemistry & geophysics Spatial distribution 01 natural sciences Seismic wave Sequence (geology) Geophysics Seismic velocity General Earth and Planetary Sciences Surface layer Seismology Aftershock Geology 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Research Letters. 44:7766-7772 |
| ISSN: | 0094-8276 |
| Popis: | We investigate seismic wave velocity structure and spatial distribution of the seismicity in the source region of the 2016 Kumamoto earthquake sequence. A one-dimensional mean velocity shows that the seismogenic zone has a high-velocity and low-Vp/Vs ratio relative to the average velocity structure of Kyushu Island. This indicates that the crust is relatively strong, capable of sustaining sufficiently high strain energy to facilitate two large (Mj > 6.5) earthquakes in close proximity to one another in rapid succession. Three-dimensional tomography of the seismogenic zone around the source of the 2016 Kumamoto earthquake sequence yields Vp = 6 km/s and Vs = 3.5 km/s. Most large-displacement areas (asperities) of the Mj 7.3 event overlap with the seismogenic zone and the overlying surface layer. Aftershock seismicity is distributed deeper than the conventional seismogenic zone, which suggests decreased strength due to fluids or increased stress, both caused by coseismic slip. |
| Databáze: | OpenAIRE |
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