Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125
Abstract We quantitatively examined the influence of pore fluid pressure and coseismic stress changes on the seismicity rate changes that followed the 2016 Kumamoto earthquake, on the basis of two approaches. One is a numerical calculation of the classic stress metric of ∆CFS, and the other is an in...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2021-01-01
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| Series: | Earth, Planets and Space |
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| Online Access: | https://doi.org/10.1186/s40623-020-01329-5 |
| _version_ | 1818591467069767680 |
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| author | Kodai Nakagomi Toshiko Terakawa Satoshi Matsumoto Shinichiro Horikawa |
| author_facet | Kodai Nakagomi Toshiko Terakawa Satoshi Matsumoto Shinichiro Horikawa |
| author_sort | Kodai Nakagomi |
| collection | DOAJ |
| description | Abstract We quantitatively examined the influence of pore fluid pressure and coseismic stress changes on the seismicity rate changes that followed the 2016 Kumamoto earthquake, on the basis of two approaches. One is a numerical calculation of the classic stress metric of ∆CFS, and the other is an inversion analysis of pore fluid pressure fields with earthquake focal mechanism data. The former calculation demonstrated that seismicity rate changes were consistent with the expectation from ∆CFS in 65% of the target region, whereas they were not in the remaining 35% of the region. The latter analysis indicates that seismicity rates increased in the regions where pore fluid pressure before the Kumamoto earthquake sequence was remarkably enhanced above hydrostatic, regardless of values of ΔCFS. This suggests that the increase in pore fluid pressure is one of the important physical mechanisms triggering aftershock generation. We obtained evidence that pore fluid pressure increased around the southern part of the main rupture zone after the mainshock, examining temporal changes in types of focal mechanism data. The average increases in pore fluid pressure were estimated to be 17, 20, and 17 MPa at depths of 5, 10, and 15 km, respectively. These large increases in pore fluid pressure cannot be explained under the undrained condition. The spatial derivative of the pore fluid pressure field in the depth direction implies that fluid supply from greater depths may have controlled increases in seismicity rates that followed the large earthquake. |
| first_indexed | 2024-12-16T10:12:54Z |
| format | Article |
| id | doaj.art-ac69452fb897469c97e9a54d8e803744 |
| institution | Directory Open Access Journal |
| issn | 1880-5981 |
| language | English |
| last_indexed | 2024-12-16T10:12:54Z |
| publishDate | 2021-01-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Earth, Planets and Space |
| spelling | doaj.art-ac69452fb897469c97e9a54d8e8037442022-12-21T22:35:32ZengSpringerOpenEarth, Planets and Space1880-59812021-01-0173111610.1186/s40623-020-01329-5Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125Kodai Nakagomi0Toshiko Terakawa1Satoshi Matsumoto2Shinichiro Horikawa3Graduate School of Environmental Studies, Nagoya UniversityGraduate School of Environmental Studies, Nagoya UniversityInstitute of Seismology and Volcanology, Kyushu UniversityTechnical Center of Nagoya University, Nagoya UniversityAbstract We quantitatively examined the influence of pore fluid pressure and coseismic stress changes on the seismicity rate changes that followed the 2016 Kumamoto earthquake, on the basis of two approaches. One is a numerical calculation of the classic stress metric of ∆CFS, and the other is an inversion analysis of pore fluid pressure fields with earthquake focal mechanism data. The former calculation demonstrated that seismicity rate changes were consistent with the expectation from ∆CFS in 65% of the target region, whereas they were not in the remaining 35% of the region. The latter analysis indicates that seismicity rates increased in the regions where pore fluid pressure before the Kumamoto earthquake sequence was remarkably enhanced above hydrostatic, regardless of values of ΔCFS. This suggests that the increase in pore fluid pressure is one of the important physical mechanisms triggering aftershock generation. We obtained evidence that pore fluid pressure increased around the southern part of the main rupture zone after the mainshock, examining temporal changes in types of focal mechanism data. The average increases in pore fluid pressure were estimated to be 17, 20, and 17 MPa at depths of 5, 10, and 15 km, respectively. These large increases in pore fluid pressure cannot be explained under the undrained condition. The spatial derivative of the pore fluid pressure field in the depth direction implies that fluid supply from greater depths may have controlled increases in seismicity rates that followed the large earthquake.https://doi.org/10.1186/s40623-020-01329-5Seismicity rate changeAftershockPore fluid pressureStressCoulomb failure stress changes2016 Kumamoto earthquake |
| spellingShingle | Kodai Nakagomi Toshiko Terakawa Satoshi Matsumoto Shinichiro Horikawa Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 Earth, Planets and Space Seismicity rate change Aftershock Pore fluid pressure Stress Coulomb failure stress changes 2016 Kumamoto earthquake |
| title | Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 |
| title_full | Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 |
| title_fullStr | Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 |
| title_full_unstemmed | Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 |
| title_short | Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan Version 2021125 |
| title_sort | stress and pore fluid pressure control of seismicity rate changes following the 2016 kumamoto earthquake japan version 2021125 |
| topic | Seismicity rate change Aftershock Pore fluid pressure Stress Coulomb failure stress changes 2016 Kumamoto earthquake |
| url | https://doi.org/10.1186/s40623-020-01329-5 |
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