scholarly journals Electrical conductive fluid-rich zones and their influence on the earthquake initiation, growth, and arrest processes: Observations from the 2016 Kumamoto earthquake sequence, Kyushu Island, Japan

2020 ◽  
Author(s):  
Koki Aizawa ◽  
Shinichi Takakura ◽  
Hisafumi Asaue ◽  
Katsuaki Koike ◽  
Ryokei Yoshimura ◽  
...  
Keyword(s):  
Broad Band ◽  
Quantitative Relationship ◽  
Outer Edge ◽  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Magnetotelluric Data ◽  
Kumamoto Earthquake ◽  
Crustal Earthquakes ◽  
The 2016 Kumamoto Earthquake ◽  
Earthquake Ruptures

Abstract Crustal earthquake ruptures tend to initiate near fluid-rich zones. However, it is relatively unknown whether fluid-rich zones can further promote or arrest these ruptures. We image the electrical resistivity structure around the focal area of the 2016 Kumamoto earthquake sequence by using 200 sites broad-band magnetotelluric data, and discuss its quantitative relationship to earthquake initiation, growth, and arrest processes. The ruptures that initiated along the outer edge of the low-resistivity fluid-rich zones (<30 Ωm) tended to become large earthquakes, whereas those that initiated either distal to or within the fluid-rich zones did not. The ruptures were arrested by high-temperature (>400°C) fluid-rich zones, whereas shallower low-temperature (200–400°C) fluid-rich zones either promoted or arrested the ruptures. These results suggest that the distribution of mid-crustal fluids contributes to the initiation, growth, and arrest of crustal earthquakes. The pre-failure pressure/temperature gradient (spatial difference) of the pore fluids may contribute to the rupture initiation, propagation, and arrest.

scholarly journals Electrical conductive fluid-rich zones and their influence on the earthquake initiation, growth, and arrest processes: observations from the 2016 Kumamoto earthquake sequence, Kyushu Island, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Koki Aizawa ◽  
Shinichi Takakura ◽  
Hisafumi Asaue ◽  
Katsuaki Koike ◽  
Ryokei Yoshimura ◽  
...  
Keyword(s):  
Quantitative Relationship ◽  
Outer Edge ◽  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Magnetotelluric Data ◽  
Kumamoto Earthquake ◽  
Crustal Earthquakes ◽  
The 2016 Kumamoto Earthquake ◽  
Earthquake Ruptures ◽  
Large Earthquakes

AbstractCrustal earthquake ruptures tend to initiate near fluid-rich zones. However, it is relatively unknown whether fluid-rich zones can further promote or arrest these ruptures. We image the electrical resistivity structure around the focal area of the 2016 Kumamoto earthquake sequence by using 200 sites broadband magnetotelluric data, and discuss its quantitative relationship to earthquake initiation, growth, and arrest processes. The ruptures that initiated along the outer edge of the low-resistivity fluid-rich zones (< 30 Ωm) tended to become large earthquakes, whereas those that initiated either distal to or within the fluid-rich zones did not. The ruptures were arrested by high-temperature (> 400 °C) fluid-rich zones, whereas shallower low-temperature (200–400 °C) fluid-rich zones either promoted or arrested the ruptures. These results suggest that the distribution of mid-crustal fluids contributes to the initiation, growth, and arrest of crustal earthquakes. The pre-failure pressure/temperature gradient (spatial difference) of the pore fluids may contribute to the rupture initiation, propagation, and arrest.

scholarly journals Electrical Conductive Fluidized Zones and Their Influence on the Earthquake Nucleation, Growth, and Arrest Processes of the 2016 Kumamoto Earthquake Sequence, Kyushu Island, Japan

2020 ◽  
Author(s):  
Koki Aizawa ◽  
Shinichi Takakura ◽  
Hisafumi Asaue ◽  
Katsuaki Koike ◽  
Ryokei Yoshimura ◽  
...  
Keyword(s):  
Broad Band ◽  
Quantitative Relationship ◽  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Magnetotelluric Data ◽  
Low Resistivity ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Earthquake Nucleation ◽  
Nucleation Growth

Abstract Crustal earthquake ruptures tend to nucleate near fluidized zones. However, it is relatively unknown whether fluidized zones can further promote or arrest these ruptures. We image the electrical resistivity structure around the focal area of the 2016 Kumamoto earthquake sequence by using 200 sites broad-band magnetotelluric data, and discuss its quantitative relationship to earthquake nucleation, growth, and arrest processes. The result shows that the earthquake hypocenters are all located within 10 km from low-resistivity fluidized zones < 30Ωm. The ruptures that nucleated along the outer edge of the low-resistivity fluidized zones tended to become large earthquakes, whereas those that initiated either distal to or within the fluidized zones did not. The ruptures were arrested by high-temperature (>400°C) fluidized zones, whereas shallower low-temperature (200°C–400°C) fluidized zones either promoted or arrested the ruptures. These results suggest that the distribution of mid-crustal fluids contributes to the nucleation, growth, and arrest of crustal earthquakes.

scholarly journals Geotechnical and infrastructural damage due to the 2016 Kumamoto earthquake sequence

2018 ◽  
Vol 104 ◽  
pp. 390-394 ◽  
Author(s):  
S. Bhattacharya ◽  
M. Hyodo ◽  
G. Nikitas ◽  
B. Ismael ◽  
H. Suzuki ◽  
...  
Keyword(s):  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake

scholarly journals Strong motions observed by K-NET and KiK-net during the 2016 Kumamoto earthquake sequence

2017 ◽  
Vol 69 (1) ◽  
Author(s):  
Wataru Suzuki ◽  
Shin Aoi ◽  
Takashi Kunugi ◽  
Hisahiko Kubo ◽  
Nobuyuki Morikawa ◽  
...  
Keyword(s):  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake

scholarly journals Characteristics of the surface ruptures associated with the 2016 Kumamoto earthquake sequence, central Kyushu, Japan

2016 ◽  
Vol 68 (1) ◽  
Author(s):  
Yoshiki Shirahama ◽  
Masayuki Yoshimi ◽  
Yasuo Awata ◽  
Tadashi Maruyama ◽  
Takashi Azuma ◽  
...  
Keyword(s):  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Surface Ruptures

Fault stressing in the overriding plate due to megathrust coupling along the Nankai trough, Japan

2020 ◽  
Author(s):  
Akinori Hashima ◽  
Hiroshi Sato ◽  
Tatsuya Ishiyama ◽  
Andrew Freed ◽  
Thorsten Becker
Keyword(s):  
Nankai Trough ◽  
Plate Boundary ◽  
Seismic Inversion ◽  
The Sea Of Japan ◽  
2016 Kumamoto Earthquake ◽  
Kumamoto Earthquake ◽  
Crustal Earthquakes ◽  
The 2016 Kumamoto Earthquake ◽  
Sw Japan ◽  
Stressing Rate

&lt;p&gt;The Nankai trough has hosted ~M8 interplate earthquakes with the interval of 100-200 years. The crustal activity in southwest (SW) Japan in the overriding plate was relatively quiet after the last coupled megathrust ruptures occurred in 1944 and 1946. In the recent 20 years, however, SW Japan has experienced ~M7 earthquakes such as the 2016 Kumamoto earthquake. Similar activation of crustal earthquakes in the later stage of the megathrust earthquake cycles can be found in the historical earthquake occurrence based on paleographical studies. Such a change cannot be resolved by the probabilistic approaches, which usually rely on paleo-seismological data on longer timescales. Here, we show a deterministic way to quantify the current stressing state on the source faults due to megathrust coupling at the Nankai trough, making use of the data captured by the dense, modern geodetic network in Japan.&lt;/p&gt;&lt;p&gt;We constructed a 3-D finite element model (FEM) around the Japanese islands including the viscoelastic feature in the asthenosphere. The geometry of plate boundary on the Philippine Sea slab is based on earthquake distributions determined by the previous studies. In particular, the bended geometry at the junction of the Nankai trough and the Ryukyu trench is crucial for calculating stress. The plate boundary is divided into 8 x 27 patches to generate Green&amp;#8217;s functions. The model region is divided into about 1000,000 tetrahedral elements with dimension of 5-100 km. We revised the source fault model by the Headquarters for Earthquake Research Promotion based on recent geophysical and geological data and added new faults in the Sea of Japan.&lt;/p&gt;&lt;p&gt;Our inter-seismic inversion suggests ~8 cm/year slip-rate deficit, which is consistent with the previous studies. Using the slip distribution, we calculate stressing rates on the source faults over SW Japan. In particular, positive Coulomb stressing rate on the source faults of the 2016 Kumamoto earthquake and the other M7 earthquakes is consistent with their occurrence. The crustal earthquakes before the 1944 and 1946 megathrust events also occurred in the region with source faults with positive Coulomb stressing rate.&lt;/p&gt;

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