A warm slab thermal structure plays an important role in controlling seismic properties of the slab and mantle wedge. Among warm subduction zones, most notably in southwest Japan, the spatial distribution of large S-wave delay times and deep nonvolcanic tremors in the forearc mantle indicate the presence of a serpentinite layer along the slab interface. However, the conditions under which such a layer is generated remains unclear. Using numerical models, we here show that a serpentinite layer begins to develop by the slab-derived fluids below the deeper end of the slab-mantle decoupling interface and grows toward the corner of the mantle wedge along the interface under warm subduction conditions only, explaining the large S-wave delay times in the forearc mantle. The serpentinite layer then allows continuous free-fluid flow toward the corner of the mantle wedge, presenting possible mechanisms for the deep nonvolcanic tremors in the forearc mantle.
|Publication status||Published - 2021 Jul|
Bibliographical noteFunding Information:
C.L. acknowledges support from the National Research Foundation of Korea (2017R1A6A1A07015374 and 2019R1A2C1002517) and the Yonsei University Research Fund (2019-22-0010). Y.K. acknowledges support from the Creative Pioneering Researchers Program of Seoul National University (SNU SRnD 3345-20160014) and the National Research Foundation of Korea (NRF-2019R1G1A1094833)
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