Open AccessCrustal structure and fluid distribution beneath the southern part of the H idaka collision zone revealed by 3‐ D electrical resistivity modeling
Author(s) -
Ichihara Hiroshi,
Mogi Toru,
Tanimoto Kengo,
Yamaya Yusuke,
Hashimoto Takeshi,
Uyeshima Makoto,
Ogawa Yasuo
Publication year - 2016
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2015gc006222
Subject(s) - geology , crust , magnetotellurics , peridotite , island arc , electrical resistivity and conductivity , collision , upwelling , arc (geometry) , seismology , collision zone , slab , mantle (geology) , petrology , geophysics , subduction , tectonics , geometry , oceanography , computer security , mathematics , computer science , electrical engineering , engineering
The Hidaka collision zone, where the Kurile and northeastern (NE) Japan arcs collide, provides a useful study area for elucidating the processes of arc‐continent evolution and inland earthquakes. To produce an image of the collision structure and elucidate the mechanisms of anomalously deep inland earthquakes such as the 1970 Hidaka earthquake (M6.7), we conducted magnetotelluric observations and generated a three‐dimensional resistivity distribution in the southern part of the Hidaka collision zone. The modeled resistivity was characterized by a high resistivity area in the upper crust of the Kurile arc corresponding to metamorphic rocks. The model also showed conductive zones beneath the center of the collision zone. The boundary between the resistive and conductive areas corresponds geometrically to the Hidaka main thrust, which is regarded as the arc‐arc boundary. The correspondence supports the collision model that the upper‐middle part of crust in the Kurile arc is obducting over the NE Japan arc. The conductive areas were interpreted as fluid‐filled zones associated with collision processes and upwelling of dehydrated fluid from the subducting Pacific slab. The fluid flow possibly contributes to over‐pressurized conduction that produces deep inland earthquakes. We also observed a significant conductive anomaly beneath the area of Horoman peridotite, which may be related to the uplift of mantle materials to the surface.