Back‐Arc Opening in the Western End of the Okinawa Trough Revealed From GNSS/Acoustic Measurements

We measured seafloor movement using a Global Navigation Satellite Systems (GNSS)/Acoustic technique at the south of the rifting valley in the western end of the Okinawa Trough back‐arc basin, 60 km east of northeastern corner of Taiwan. The horizontal position of the seafloor benchmark, measured eig...

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Bibliographic Details
Published in:Geophysical research letters 2018-01, Vol.45 (1), p.137-145
Main Authors: Chen, Horng‐Yue, Ikuta, Ryoya, Lin, Cheng‐Horng, Hsu, Ya‐Ju, Kohmi, Takeru, Wang, Chau‐Chang, Yu, Shui‐Beih, Tu, Yoko, Tsujii, Toshiaki, Ando, Masataka
Format: Article
Language:English
Subjects:
Acoustic measurement
Acoustic navigation
Acoustics
Average velocity
back‐arc basin
Benchmarks
Global navigation satellite system
GNSS/Acoustic
Horizontal orientation
Intrusion
Lava
Navigation
Navigation satellites
Ocean floor
Okinawa trough
Position measurement
Rifting
rifting valley
Ryukyu arc
Satellites
seafloor geodesy
Seismic activity
Seismicity
Valleys
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Summary:We measured seafloor movement using a Global Navigation Satellite Systems (GNSS)/Acoustic technique at the south of the rifting valley in the western end of the Okinawa Trough back‐arc basin, 60 km east of northeastern corner of Taiwan. The horizontal position of the seafloor benchmark, measured eight times between July 2012 and May 2016, showed a southeastward movement suggesting a back‐arc opening of the Okinawa Trough. The average velocity of the seafloor benchmark shows a block motion together with Yonaguni Island. The westernmost part of the Ryukyu Arc rotates clockwise and is pulled apart from the Taiwan Island, which should cause the expansion of the Yilan Plain, Taiwan. Comparing the motion of the seafloor benchmark with adjacent seismicity, we suggest a gentle episodic opening of the rifting valley accompanying a moderate seismic activation, which differs from the case in the segment north off‐Yonaguni Island where a rapid dyke intrusion occurs with a significant seismic activity. Key Points Crustal motion near back‐arc rift valley is monitored using GNSS/Acoustic geodesy Episodic opening of back arc rift valley is observed, which may have progressed gradually within a few months Western end of the Ryukyu arc behaves as a block rotating clockwise, which should pull the northwestern end of Taiwan Island to the east
ISSN:0094-8276
1944-8007
DOI:10.1002/2017GL075724