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

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 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

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 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

GNSS-A seafloor geodetic observation capability in 2021 and its applicability to global geodesy

2021 ◽  
Author(s):  
Yusuke Yokota ◽  
Tadashi Ishikawa ◽  
Shun-ichi Watanabe ◽  
Yuto Nakamura
Keyword(s):  
Reference Frame ◽  
Scientific Data ◽  
Coast Guard ◽  
High Rate ◽  
Plate Motion ◽  
Small Scale ◽  
Coupling Condition ◽  
Geodetic Observation ◽  
Seafloor Geodetic Observation ◽  
Euler Pole

<p>Recently, the GNSS-A (Global Navigation Satellite System – Acoustic combination technique) seafloor geodetic observation technology, developed in the Hydrographic and Oceanographic department in Japan Coast Guard (JCG), was upgraded to be able to monitor a subseafloor interplate coupling condition of about 1 cm/year and an interplate shallow slow slip event of about 5 cm (e.g., Yokota et al., 2018, Scientific Data; Ishikawa et al., 2020, Front. Ear. Sci.). By observing such small-scale seafloor crustal movements, GNSS-A technology makes a decisive contribution to subduction seismology and disaster prevention sciences (e.g., Yokota et al., 2016, Nature; Yokota and Ishikawa, 2020, Sci. Adv.). This technology was achieved by connecting high-precision underwater acoustic ranging technology and high-rate GNSS on a vessel at sea surface.</p><p>The GNSS-A, which is carried out all over the world, especially in the Pacific Rim, has been constructed for observation of plate boundary subduction processes and fault movement processes. Unlike the GNSS network, GNSS-A has never contributed to global geodesy within the framework of the Global Geodetic Observing System (GGOS). However, it can be a unique observation method for the construction of the International Terrestrial Reference Frame (ITRF). It can make an important contribution in determining the movement and Euler pole on an oceanic plate that have few land area.</p><p>In the future, if an extensive seafloor geodetic observation network as shown by Kato et al. (2018, JDR) will be established, there is a possibility of constructing a next-generation reference frame that completely explains the plate motion on the earth's surface. This presentation will present the current state of the GNSS-A ability and cost and future prospects for the contribution to global geodesy.</p>

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