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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/45407

Title: Thermal modeling of the SW Ryukyu forearc (Taiwan): Implications for the seismogenic zone and the age of the subducting Philippine Sea Plate (Huatung Basin)
Authors: M.-A.Gutscher;F.Klingelhoefer;T.Theunissen;W.Spakmand;T.Berthet;T.K.Wang;C.-S.Lee
Contributors: 國立臺灣海洋大學:應用地球科學研究所
Keywords: Subduction;Finite-element modeling;Forearc thermal structure;Seismogenic zone
Date: 2016-12
Issue Date: 2018-03-16T07:51:34Z
Publisher: Tectonophysics
Abstract: Abstract:Subduction mega-thrust earthquakes in the SW Ryukyu trench pose a seismic and tsunami hazard. One of the objectives of this study is to estimate the downdip width of the seismogenic zone using numerical modeling to determine the temperature distribution along the plate interface. However, this approach depends strongly on the thermal parameters of the subducting slab. While the Philippine Sea plate (PSP) subducting beneath the central and eastern Ryukyu arc is of Eocene age (35–50 Ma), its age west of the Gagua Ridge is uncertain, with proposed ages ranging from Lower Cretaceous (140 Ma) to Upper Eocene (35 Ma). Since the sparse available heat flow data are insufficient to resolve this debate, both end-member hypotheses are tested as input parameters. We examined two transects at 122.5°E and 123.5°E on either side of the N-S trending, 4-km high, Gagua Ridge. The shallow forearc geometry is obtained from wide-angle seismic data. The deep slab geometry was obtained from hypocenter distribution and tomography. For an Eocene slab age, we obtain a 100 km and 110 km wide seismogenic zone (between the 150 °C and 350 °C isotherms) west and east of Gagua Ridge, respectively. This is in good agreement with the observed distribution of hypocenters. Using a Cretaceous slab west of Gagua Ridge predicts a deep seismogenic zone (25 km–60 km depth), inconsistent with observed thrust earthquakes. Tomographic images at 122.5°E and 123.5°E show a similar slab thickness of 70–80 km suggesting that the oceanic lithosphere has a young (Eocene) thermal age. The westernmost PSP (Huatung Basin) may have been thermally rejuvenated by mantle convection near the slab corner. The tectonic history since 6 Ma (transition from subduction to collision beneath Taiwan) may have also perturbed the thermal structure.
Relation: 692 pp.131-142
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/45407
Appears in Collections:[應用地球科學研究所] 期刊論文

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