Gradient field of undersea sound speed structure extracted from the GNSS-A oceanography

After the twenty-first century, the Global Navigation Satellite System-Acoustic ranging (GNSS-A) technique detected geodetic events such as co- and postseismic effects following the 2011 Tohoku-oki earthquake and slip-deficit rate distributions along the Nankai Trough subduction zone. Although these...

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Bibliographic Details
Published in:Marine geophysical researches 2019-12, Vol.40 (4), p.493-504
Main Authors: Yokota, Yusuke, Ishikawa, Tadashi, Watanabe, Shun-ichi
Format: Article
Language:English
Subjects:
Accuracy
Crustal deformation
Deformation
Earth and Environmental Science
Earth Sciences
Earthquakes
Emergency preparedness
Feasibility studies
Geodesy
Geophysics/Geodesy
Navigation
Navigation satellites
Navigation systems
Ocean floor
Oceanographic research
Oceanography
Offshore Engineering
Original Research Paper
Satellites
Seismic activity
Seismology
Sound
Sound velocity
Spatial variations
Subduction
Subduction zones
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Summary:After the twenty-first century, the Global Navigation Satellite System-Acoustic ranging (GNSS-A) technique detected geodetic events such as co- and postseismic effects following the 2011 Tohoku-oki earthquake and slip-deficit rate distributions along the Nankai Trough subduction zone. Although these are extremely important discoveries in geodesy and seismology, more accurate observation that can capture temporal and spatial changes are required for future earthquake disaster prevention. In order to upgrade the accuracy of the GNSS-A technique, it is necessary to understand disturbances in undersea sound speed structures, which are major error sources. In particular, detailed temporal and spatial variations are difficult to observe accurately, and their effect was not sufficiently extracted in previous studies. In the present paper, we reconstruct an inversion scheme for extracting the effect from GNSS-A data and experimentally apply this scheme to the seafloor sites around the Kuroshio. The extracted gradient effects are believed to represent not only a broad sound speed structure but also a more detailed structure generated in the unsteady disturbance. The accuracy of the seafloor positioning was also improved by this new method. The obtained results demonstrate the feasibility of using the GNSS-A technique to detect a seafloor crustal deformation for oceanography research.
ISSN:0025-3235
1573-0581
DOI:10.1007/s11001-018-9362-7