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Coseismic and Postseismic Crustal Deformation Associated With the 2016 Kumamoto Earthquake Sequence Revealed by PALSAR-2 Pixel Tracking and InSAR

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Title: Coseismic and Postseismic Crustal Deformation Associated With the 2016 Kumamoto Earthquake Sequence Revealed by PALSAR-2 Pixel Tracking and InSAR
Authors: Himematsu, Yuji Browse this author
Furuya, Masato Browse this author →KAKEN DB
Keywords: satellite SAR
crustal deformation
pixel tracking
Issue Date: Oct-2020
Publisher: American Geophysical Union
Journal Title: Earth and Space Science
Volume: 7
Issue: 10
Start Page: e2020EA001200
Publisher DOI: 10.1029/2020EA001200
Abstract: Coseismic and postseismic crustal deformations caused by earthquake episodes are important in understanding the mechanisms of these episodes as well as the fault rheology near an epicentral area. Specifically, interferometric synthetic aperture radar (InSAR) and synthetic aperture radar (SAR) pixel tracking can depict high-resolution crustal deformation fields associated with earthquakes and volcanic activities without installing on-site observation instruments. In this study, we investigate the coseismic and postseismic near-fault crustal deformations associated with the 2016 Kumamoto earthquake sequence in southwest Japan using ALOS-2/PALSAR-2 (Phased Array-type L-band SAR-2) data. Coseismic three-dimensional (3-D) displacement fields inferred from PALSAR-2 pixel tracking data showed 1.6 m of horizontal displacements and 2 m of subsidence at maximum, despite the mainshock focal mechanism that was dominated by strike-slip components with N-S extension axes. The locations of large displacement variations along surface ruptures due to the mainshock were almost identical to a region where infrastructure was damaged, thus implying the generation of strong ground seismic waves. By using conventional InSAR stacking, we inferred two independent quasi-east-west and quasi-vertical displacement fields as cumulative postseismic deformations following the mainshock over a period of about 2 years. The near-fault postseismic deformation represented complicated displacement characteristics that could not be explained by a single physical process. Deformation signals around Aso volcano were interpreted by the effects of postseismic physical processes as well as geological heterogeneous structures. Plain Language Summary Coseismic and postseismic crustal deformation fields provide information for inferring slip distributions occurring along a fault, and these data are helpful for understanding the geological characteristics around an epicentral area. By using satellite synthetic aperture radar (SAR) images, we can derive crustal deformation maps with high spatial resolutions and high measurement accuracy without installing on-site observation instruments. In this paper, we offer coseismic and postseismic crustal deformation maps associated with the 2016 Kumamoto earthquake sequence on Kyushu Island, SW Japan, which were derived using the Japanese SAR satellite ALOS- 2/PALSAR-2 data. Measurements of displacements along with details on Earth surface ruptures due to earthquakes also allow us to understand the variations in rupture processes along seismogenic faults. Furthermore, comparisons of the spatial and temporal variations of coseismic and postseismic deformations can provide information on the geophysical mechanisms of long-term deformations following a mainshock.
Type: article
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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