Strength of plate coupling in the southern Ryukyu subduction zone

Doo, Wen Bin; Lo, Chien-Jung; Wu, Wen Nan; Lin, Jing Yi; Hsu, Shu Kun; Huang, Yushu; Wang, Hsueh Fen

doi:10.1016/j.tecto.2017.12.028

Cited by 10 publications

(11 citation statements)

References 41 publications

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“…These geophysical observations along the Ryukyu Arc suggest that the typical locked zone is absent; however, GPS measurements from Okinawa Island, approximately 110 km from the trench, cannot detect inter-plate coupling of a seaward zone approximately 30 km wide along the trench 18 . A density structural model 19 of the Ryukyu Arc also suggested strong coupling along the plate boundary. Thus, the possibility of inter-plate coupling along the shallowest part of the plate boundary has not been excluded 11 , 18 , 19 , and the question as to whether the shallow plate boundary is coupled remains controversial.…”

Section: Introductionmentioning

confidence: 96%

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Accretionary prism collapse: a new hypothesis on the source of the 1771 giant tsunami in the Ryukyu Arc, SW Japan

Okamura

Nishizawa

Fujii

et al. 2018

Sci Rep

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The giant 1771 Yaeyama tsunami occurred in the southwestern part of the Ryukyu Arc, a region on an obliquely subducting plate boundary, which shows no direct evidence of inter-plate coupling. Studies of tsunami boulders and deposits suggest that the recurrence interval of comparably giant tsunamis is roughly 500 to 1000 years. Tsunami source models, which include either slip on a shallow plate boundary or active faulting plus a landslide on the overriding plate, are controversial because of inconsistencies in the geophysical and geological data. We discovered a seafloor depression that is approximately 30 km wide and 80 km long extending in the ESE-WNW direction. This depression is accompanied by a seaward bulge on the accretionary prism along the Ryukyu Trench, which is based on detailed bathymetric data and interpreted to be the result of accretionary prism collapse and seaward displacement by rotational slide. A simple tsunami simulation shows that the slide is a plausible source of the 1771 tsunami. We propose a collapse model, in which the accretionary prism remained over-steepened as strike-slip faulting removed the prism toe. Our model indicates that some oblique subduction zones are capable of generating giant tsunamis regardless of weak or strong coupling.

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Section: Introductionmentioning

confidence: 96%

“…A density structural model 19 of the Ryukyu Arc also suggested strong coupling along the plate boundary. Thus, the possibility of inter-plate coupling along the shallowest part of the plate boundary has not been excluded 11 , 18 , 19 , and the question as to whether the shallow plate boundary is coupled remains controversial.…”

Section: Introductionmentioning

confidence: 96%

Accretionary prism collapse: a new hypothesis on the source of the 1771 giant tsunami in the Ryukyu Arc, SW Japan

Okamura

Nishizawa

Fujii

et al. 2018

Sci Rep

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“…Recently, Lin et al () showed that several geological and geophysical similarities exist between the Sumatra and the Ryukyu subduction zones (the stress regime, the presence of subducting reliefs and high gravity anomalies, and the distribution of the seismicity) and concluded that a megathrust event is highly likely, particularly in the central Ryukyu Arc. Moreover, based on a new lithospheric density model, Doo et al () inferred a strong plate coupling in southern Ryukyu.…”

Section: Introductionmentioning

confidence: 99%

Relative Sea‐Level Changes Over the Past Centuries in the Central Ryukyu Arc Inferred From Coral Microatolls

et al. 2020

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This study focuses on Okinawa and Yoron islands, in order to better understand tectonics in the Ryukyu Arc related to the subduction zone. We used coral microatolls—known for their centimetric accuracy in the record of relative sea‐level (RSL) changes—to reconstruct RSL changes over the last century from living microatolls. A fossil microatoll in Yoron was used to discuss possible RSL changes beyond the last century. The signal consists of emergence whose rate varies through time, interrupted by decadal to multidecadal periods of sudden and/or gradual submergence and by interannual sea‐level falls. Comparison with other existing RSL records in the arc highlights RSL variability along the arc. This pattern contrasts with the homogeneous and linear absolute regional sea‐level rise, implying that this latter signal cannot fully explain our observations and that an additional process is required. We suggest the subduction zone as a possible source for generating centimetric scale RSL changes observed in coral microatolls. We tested how the Ryukyu megathrust could explain our observations with elastic dislocation modeling. The emergence trend could be explained by interseismic loading on the plate interface with a minimum coupling rate of 25%, which is higher than previous estimates based on short instrumental records. As for the submergence events that occurred regularly in the coral record, we show that they could be explained by slow slip events on the shallower part of the megathrust or in the transition zone. Such process could accommodate a significant part of the total convergence.

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“…The Ryukyu Trench was formed as a result of the subduction of the oceanic crust of the Philippine Sea Plate beneath the continental crust of the Eurasian Plate (Doo et al, 2018). The tectonic settings of the Ryukyu Trench reflect the evolutional processes of the building seamounts and structure of the Earth's crust.…”

Section: Tectonicsmentioning

confidence: 99%

Using GMT for 2D and 3D Modeling of the Ryukyu Trench Topography, Pacific Ocean

Lemenkova

2021

Miscellanea Geographica

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This research focuses on the 2D and 3D geospatial analysis of the Ryukyu Trench, a deep-sea trench located in the western Pacific Ocean between Japan and Taiwan. The aim of the research is to visualize regional differences in the topography of the southern (S) and northern (N) parts of the trench. Technically, the methodology is based on using the Generic Mapping Tools (GMT) scripting toolset, for modelling the General Bathymetric Chart of the Oceans (GEBCO), and Earth Topography and Bathymetry dataset (ETOPO1) raster grids. The results demonstrated topographic differences in the two segments. The most frequent depths lie between -5,000 and -6,000 m. The N part has steeper gradient slopes and deeper bathymetry. Of the depth differences >-6,000 m, S has nine values with depths >-6,800 m while N shows 123 records (max -7,460 m). The submarine terraces of S have gentler slopes compared with the N segment. The technical approach presents GMT-based 2D and 3D cartographic modelling aimed at visualizing regional variations of the seafloor topography.

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Strength of plate coupling in the southern Ryukyu subduction zone

Cited by 10 publications

References 41 publications

Accretionary prism collapse: a new hypothesis on the source of the 1771 giant tsunami in the Ryukyu Arc, SW Japan

Accretionary prism collapse: a new hypothesis on the source of the 1771 giant tsunami in the Ryukyu Arc, SW Japan

Relative Sea‐Level Changes Over the Past Centuries in the Central Ryukyu Arc Inferred From Coral Microatolls

Using GMT for 2D and 3D Modeling of the Ryukyu Trench Topography, Pacific Ocean

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