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Three‐Dimensional Electrical Resistivity Structure Beneath a Volcanically and Seismically Active Island, Kyushu, Southwest Japan Arc
Author(s) -
Hata M.,
Munekane H.,
Utada H.,
Kagiyama T.
Publication year - 2020
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2019jb017485
Subject(s) - geology , volcano , subduction , seismology , slab , island arc , front (military) , tectonics , volcanic arc , mantle (geology) , volcanic belt , electrical resistivity and conductivity , volcanic rock , geomorphology , geochemistry , paleontology , oceanography , electrical engineering , engineering
To understand the subduction dynamics around Kyushu Island, Southwest Japan Arc, the distribution of fluids is imaged by resolving three‐dimensional (3‐D) electrical resistivity structure beneath a subregion the island, including volcanic and nonvolcanic areas. The nonvolcanic region in central Kyushu is situated between two regions with numerous Quaternary volcanic structures along a volcanic front aligned N30°E and related to subduction of the Philippine Sea Plate. Two source areas of slow slip events lie at depths of 20–40 km along the eastern coast of Kyushu, whereas earthquakes spread along the subducting Philippine Sea Plate plane over the eastern coast and toward the volcanic front at depths of 20 to >100 km. Our 3‐D resistivity model detects prominent conductors, indicating the presence of fluids, which might control volcanic and seismic activity. The most robust features of the model are three regions of high conductivity. A magma system and a fluid system are imaged as two vertical conductors extending from a depth of ~70 km, both related to slab‐derived fluid and located along the volcanic front, beneath the volcanic and nonvolcanic regions, respectively. The third conductor, which suggests the presence of slab‐derived fluid and hydrated sediments at the plate interface and the presence of serpentinite in the mantle wedge, appears in an area devoid of slow slip events at depths of <~30 km along the southeastern coast.