scholarly journals Interplate locking condition derived from seafloor geodetic observation in the shallowest subduction segment at the Central Nankai Trough, Japan

2017 ◽  
Vol 44 (8) ◽  
pp. 3572-3579 ◽  
Author(s):  
Kenji Yasuda ◽  
Keiichi Tadokoro ◽  
Sota Taniguchi ◽  
Hiroshi Kimura ◽  
Kenjiro Matsuhiro
Keyword(s):  
Nankai Trough ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation

scholarly journals Heterogeneous interplate coupling along the Nankai Trough, Japan, detected by GPS-acoustic seafloor geodetic observation

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Yusuke Yokota ◽  
Tadashi Ishikawa ◽  
Mariko Sato ◽  
Shun-ichi Watanabe ◽  
Hiroaki Saito ◽  
...  
Keyword(s):  
Nankai Trough ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation ◽  
Interplate Coupling

Routine seafloor geodetic observation around Japan

2005 ◽  
Author(s):  
M. Mochizuki ◽  
M. Fujita ◽  
M. Sato ◽  
Z. Yoshida ◽  
T. Yabuki ◽  
...  
Keyword(s):  
Geodetic Observation ◽  
Seafloor Geodetic Observation

scholarly journals Crustal Deformation Detection Capability Associated With a Fault Slip on the Interplate Boundary in the Gnss-a Seafloor Geodetic Observation Array (SGO-A), Provided By Japan Coast Guard

2021 ◽  
Author(s):  
Yusuke Yokota ◽  
Tadashi Ishikawa ◽  
Sun-ichi Watanabe ◽  
Yuto Nakamura
Keyword(s):  
Standard Deviation ◽  
Crustal Deformation ◽  
Deformation Rate ◽  
Coast Guard ◽  
Detection Sensitivity ◽  
Japan Trench ◽  
Detection Capability ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation ◽  
Slip Event

Abstract The GNSS-A technique is an observation method that can detect seafloor crustal deformations with centimeter level accuracy. The GNSS-A seafloor geodetic observation array operated by the Japan Coast Guard, called SGO-A, has been constructed near the Japan Islands along the Nankai Trough and the Japan Trench. This observation array has detected several earthquakes’ displacements and episodic slow crustal deformation. To compare the detection results of SGO-A with other observation networks and expand the SGO-A distribution, it is necessary to correctly understand its detection capability. In this paper, the capabilities of current GNSS-A (frequency: f = 4–6 times/year, position accuracy: σ (standard deviation) = 1.5 cm) to detect a crustal deformation rate only, an event only, and crustal deformation rate and event together were arranged by numerical simulations. Results suggested the following features: when it is known that there is no event, the 95% confidence level (CL) for the estimation of crustal deformation rate with 4-year observation is about 0.5–0.8 cm/year; when the deformation rate is known, a signal of about 3.0 cm can be detected by observations of about 4 times before and after the event. When the deformation rate and the event are detected together, to keep the false positive low (about 0.05), the false negative becomes high (about 0.2–0.7 for detecting a signal of 4.5–6.0 cm). The determined rate and event variations are approximately 1.8 cm/year (95%CL) and 1.5 cm (standard deviation), respectively. We also examined the detection capability for higher frequency and accuracy, to examine how the detection capability improves by technological advancements in the future. Additionally, we calculated the spatial range of event detectability using the determined values of detection sensitivity. Each seafloor site can detect a slip event larger than 0.1 m scale within about 50 km radius. A subseafloor slip event smaller than about 1 m at the distance of 100 km or more from the land can often be detected only on the seafloor observation array.

scholarly journals Restoration of interplate locking after the 2005 Off-Miyagi Prefecture earthquake, detected by GPS/acoustic seafloor geodetic observation

2011 ◽  
Vol 38 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Mariko Sato ◽  
Hiroaki Saito ◽  
Tadashi Ishikawa ◽  
Yoshihiro Matsumoto ◽  
Masayuki Fujita ◽  
...  
Keyword(s):  
Geodetic Observation ◽  
Seafloor Geodetic Observation ◽  
Miyagi Prefecture

scholarly journals Undersea co-seismic crustal movements associated with the 2005 Off Miyagi Prefecture Earthquake detected by GPS/acoustic seafloor geodetic observation

2006 ◽  
Vol 58 (12) ◽  
pp. 1573-1576 ◽  
Author(s):  
Yoshihiro Matsumoto ◽  
Masayuki Fujita ◽  
Tadashi Ishikawa ◽  
Masashi Mochizuki ◽  
Tetsuichiro Yabuki ◽  
...  
Keyword(s):  
Geodetic Observation ◽  
Crustal Movements ◽  
Seafloor Geodetic Observation ◽  
Miyagi Prefecture

scholarly journals Crustal deformation detection capability of the GNSS-A seafloor geodetic observation array (SGO-A), provided by Japan Coast Guard

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yusuke Yokota ◽  
Tadashi Ishikawa ◽  
Shun-ichi Watanabe ◽  
Yuto Nakamura
Keyword(s):  
Standard Deviation ◽  
Crustal Deformation ◽  
Deformation Rate ◽  
Nankai Trough ◽  
Coast Guard ◽  
Detection Capability ◽  
Positioning Accuracy ◽  
Transient Event ◽  
Seafloor Geodetic Observation ◽  
Slip Event

AbstractThe GNSS-A technique is an observation method that can detect seafloor crustal deformations with centimeter-level positioning accuracy. The GNSS-A seafloor geodetic observation array operated by the Japan Coast Guard (SGO-A) has been constructed near the Japanese Islands along the Nankai Trough and the Japan Trench. This observation array has detected several earthquakes’ displacements and episodic slow crustal deformation. To compare the detection results of SGO-A with other observation networks and expand the SGO-A coverage area, it is necessary to correctly understand its detection capability. In this paper, numerical simulations and statistical verifications were used to assess the capabilities of the present GNSS-A system using a manned vessel (observation frequency: 4–6 times/year, positioning accuracy: standard deviation = 1.5 cm) to detect (1) secular deformation only, (2) a transient slip event only and (3) secular deformation and a transient event together. We verified these results with appropriate thresholds and found the following features: When it is known that there is no transient event, the 95% confidence level (CL) for the estimation of secular crustal deformation rate with 4-year observation is about 0.5–0.8 cm/year; when the deformation rate is known, a signal of about 3.0 cm can be detected by observations of about 4 times before and after the transient event. When the deformation rate and the transient event are detected together, to keep the false positive low (about 0.05), the false negative becomes high (about 0.7–0.2 for detecting a signal of 4.5–6.0 cm). The determined rate and event variations are approximately 1.8 cm/year (95%CL) and 1.5 cm (standard deviation), respectively. We also examined the detection capability for higher observation frequency and positioning accuracy, to examine how the detection capability improves by technological advancements in the future. Additionally, we calculated the spatial range of event detectability using the determined values of detection sensitivity. Obtained results show that each seafloor site can detect a slip event of < 1.0 m scale within about 30 km radius, and approximately one-third of the subseafloor slip event over 100 km from land along the Nankai Trough can only be detected by SGO-A.

scholarly journals GPS/Acoustic seafloor geodetic observation: method of data analysis and its application

2006 ◽  
Vol 58 (3) ◽  
pp. 265-275 ◽  
Author(s):  
Masayuki Fujita ◽  
Tadashi Ishikawa ◽  
Masashi Mochizuki ◽  
Mariko Sato ◽  
Shin-ichi Toyama ◽  
...  
Keyword(s):  
Data Analysis ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation ◽  
Observation Method

Evidence of viscoelastic deformation following the 2011 Tohoku-Oki earthquake revealed from seafloor geodetic observation

2014 ◽  
Vol 41 (16) ◽  
pp. 5789-5796 ◽  
Author(s):  
Shun-ichi Watanabe ◽  
Mariko Sato ◽  
Masayuki Fujita ◽  
Tadashi Ishikawa ◽  
Yusuke Yokota ◽  
...  
Keyword(s):  
Viscoelastic Deformation ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation
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