Japan Geoscience Union Meeting 2023

Presentation information

[E] Online Poster

S (Solid Earth Sciences ) » S-EM Earth's Electromagnetism

[S-EM14] Electric, magnetic and electromagnetic survey technologies and scientific achievements

Wed. May 24, 2023 1:45 PM - 3:15 PM Online Poster Zoom Room (4) (Online Poster)

convener:Kiyoshi Baba(Earthquake Research Institute, The University of Tokyo), Tada-nori Goto(Graduate School of Science, University of Hyogo), Yuguo Li(Ocean University of China), Wiebke Heise(GNS Science, PO Box 30368, Lower Hutt, New Zealand)

On-site poster schedule(2023/5/23 17:15-18:45)

1:45 PM - 3:15 PM

[SEM14-P12] Resistivity structure of the Pacific plate and the asthenosphere on the seaward slope of the Japan Trench, off Sanriku

*Miku Sakurai1, Tada-nori Goto1, Shinya Sato2, Hiroshi Ichihara3, Takafumi Kasaya4, Makoto Yamano5 (1.University of Hyogo, 2.Kyoto Univesity, 3.Nagoya Univesity, 4.Japan Agency for Marine-Earth Science and Technology, 5.the Univesity of Tokyo)


Keywords:Japan Trench, resistivity structure, magnetotelluric, fluid distributions, asthenosphere

The occurrence of plate boundary earthquakes is related to the presence of water in the rock. The strength of the crust depends on the water content. Therefore, it is important to investigate the distribution and quantity of water at depth for understanding the occurrence of earthquakes.
Yamano and Kawada (2016) report that fluids exist inside the oceanic plate, and the thichness of permeable layers increase towards the trench. However, it is not yet clear on the source of the fluid.
In this study, seafloor electromagnetic field surveys were carried out on the Pacific Plate far off Sanriku, Japan, to estimate the resistivity structure for discuss the deep subsurface conditions and water distributions.
Ocean bottom electromagnetometers were installed on the seafloor to record the natural fluctuations of magnetic and electric field. The data were used to estimate the subsurface resistivity structure with the magnetotelluric method.
The results obtained by the two-dimensional inversion scheme revealed the existence of a low resistivity zone in the oceanic upper mantle depth (at the asthenosphere) before the subdution. The obtained feature was similar to the published researches below the Mariana subduction zone. In the future, we will estimate the resistivity structure inthe oceanic plate. It is necessary to elucidate where the fluid exists and comes from.