Survey of Pre-seismic Change of the 2016 Kumamoto Earthquake Using Groundwater Level Data Monitored by Kumamoto-city, Japan

2017 ◽  
Vol 70 (0) ◽  
pp. 147-152
Author(s):  
Yoshiaki ORIHARA ◽  
Masashi KAMOGAWA
Keyword(s):  
Groundwater Level ◽  
2016 Kumamoto Earthquake ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Level Data

scholarly journals Seasonal and transient surface displacements in the Kumamoto area, Japan, associated with the 2016 Kumamoto earthquake: implications for seismic-induced groundwater level change

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Kazuya Ishitsuka ◽  
Takeshi Tsuji ◽  
Weiren Lin ◽  
Makoto Kagabu ◽  
Jun Shimada
Keyword(s):  
Groundwater Level ◽  
Surface Displacement ◽  
Earthquake Sequence ◽  
2016 Kumamoto Earthquake ◽  
Persistent Scatterer Interferometry ◽  
Kumamoto Earthquake ◽  
Level Change ◽  
Surface Displacements ◽  
The 2016 Kumamoto Earthquake ◽  
Groundwater Level Change

Abstract The 2016 Kumamoto earthquake sequence on April 14 (Mw 6.2) and April 16 (Mw 7.0) altered the regional groundwater level. To better understand the relationship between groundwater level change and surface displacement, we estimated surface displacement in the Kumamoto area (Japan) using persistent scatterer interferometry from 19 ALOS/PALSAR images acquired between January 7, 2007 and March 5, 2011, 28 ALOS-2/PALSAR-2 images acquired between April 17, 2016 and December 10, 2018, and 113 Sentinel-1 images acquired between May 26, 2016 and December 30, 2018. Our estimation shows that transient surface displacement occurred following the 2016 Kumamoto earthquake sequence, together with seasonal surface displacement that was not detected from the 2007–2011 images. We suggest that a portion of the transient displacement occurred via groundwater drawdown through new ruptures that formed owing to the 2016 Kumamoto earthquake sequence and sediment compaction. Seasonal surface displacements detected after the 2016 Kumamoto earthquake sequence are linked to groundwater level variations.

scholarly journals Seismic velocity structure at the southern termination of the 2016 Kumamoto Earthquake rupture, Japan

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Yasuhira Aoyagi ◽  
Haruo Kimura ◽  
Kazuo Mizoguchi
Keyword(s):  
Fault Zone ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Earthquake Rupture ◽  
2016 Kumamoto Earthquake ◽  
Seismic Velocity Structure ◽  
Kumamoto Earthquake ◽  
Seismogenic Layer ◽  
The 2016 Kumamoto Earthquake ◽  
Tectonic Line

Abstract The earthquake rupture termination mechanism and size of the ruptured area are crucial parameters for earthquake magnitude estimations and seismic hazard assessments. The 2016 Mw 7.0 Kumamoto Earthquake, central Kyushu, Japan, ruptured a 34-km-long area along previously recognized active faults, eastern part of the Futagawa fault zone and northernmost part of the Hinagu fault zone. Many researchers have suggested that a magma chamber under Aso Volcano terminated the eastward rupture. However, the termination mechanism of the southward rupture has remained unclear. Here, we conduct a local seismic tomographic inversion using a dense temporary seismic network to detail the seismic velocity structure around the southern termination of the rupture. The compressional-wave velocity (Vp) results and compressional- to shear-wave velocity (Vp/Vs) structure indicate several E–W- and ENE–WSW-trending zonal anomalies in the upper to middle crust. These zonal anomalies may reflect regional geological structures that follow the same trends as the Oita–Kumamoto Tectonic Line and Usuki–Yatsushiro Tectonic Line. While the 2016 Kumamoto Earthquake rupture mainly propagated through a low-Vp/Vs area (1.62–1.74) along the Hinagu fault zone, the southern termination of the earthquake at the focal depth of the mainshock is adjacent to a 3-km-diameter high-Vp/Vs body. There is a rapid 5-km step in the depth of the seismogenic layer across the E–W-trending velocity boundary between the low- and high-Vp/Vs areas that corresponds well with the Rokkoku Tectonic Line; this geological boundary is the likely cause of the dislocation of the seismogenic layer because it is intruded by serpentinite veins. A possible factor in the southern rupture termination of the 2016 Kumamoto Earthquake is the existence of a high-Vp/Vs body in the direction of southern rupture propagation. The provided details of this inhomogeneous barrier, which are inferred from the seismic velocity structures, may improve future seismic hazard assessments for a complex fault system composed of multiple segments.

scholarly journals Correction to: Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Kodai Nakagomi ◽  
Toshiko Terakawa ◽  
Satoshi Matsumoto ◽  
Shinichiro Horikawa
Keyword(s):  
Fluid Pressure ◽  
Pressure Control ◽  
Pore Fluid ◽  
2016 Kumamoto Earthquake ◽  
Pore Fluid Pressure ◽  
Seismicity Rate ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Seismicity Rate Changes

An amendment to this paper has been published and can be accessed via the original article.

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