[U-15] The 2024 Noto Peninsula Earthquake (1:J)

[U15-P56] Three-dimensional resistivity structure around the 2024 Noto Peninsula Earthquake

*Ryokei Yoshimura¹, Yoshihiro Hiramatsu², Tada-nori Goto³, Takafumi Kasaya⁴, Rintaro Miyamachi¹, Nakagawa Jun¹, Nagi Yamashita³, Rei Amano³, Masato Fukata², Amane Sugii², Taisei Inui¹, Kenichi Yamazaki¹, Shintaro Komatsu¹, Takuya Iwahori¹, Masahiro Yoshikawa¹, Ayako Namigishi¹, Nagaoka Airi¹, Yasuto Tatsuyama¹, Akihiro Sawada², Ce Zhang², Mitsuteru Fukuoka², Yuya Jinde², Yuki Oshima³, Momoka Kanazawa³ (1.Disaster Prevention Research Institute, Kyoto University, 2.Kanazawa University, 3.University of Hyogo, 4.Japan Agency for Marine-Earth Science and Technology)

Keywords:Noto, seismic swarm, resistivity structure

Earthquake swarm activity and localized non-steady crustal deformation had been ongoing near the city of Suzu (the northeastern Noto Peninsula), Ishikawa Prefecture, since the end of 2020. This activity began around June 2018, with a M5.1 earthquake on September 16, 2021, and a M5.4 earthquake on June 19, 2022, a M6.5 earthquake on May 5, 2023, and a M7.6 earthquake on January 1, 2024.
We have been conducting a subsurface resistivity structure surveys to elucidate the structural location of the swarm activity and to determine whether there are structural differences from the area where the 2007 Noto Peninsula earthquake occurred. The resistivity structure estimated from the onshore broadband electromagnetic field data obtained in 2021 and 2022 shows the existence of a continuous low-resistivity zone from the depth of the southern cluster where a series of seismic swarms started to the northern cluster, which is the most active area in the swarm region. Furthermore, the cluster seismic activity is almost located at the upper outer edge of this low-resistivity zone, which strongly suggests the involvement of fluid in this activity.
In this presentation, we will report on the resistivity structure of the entire northern part of the Noto Peninsula, including data from supplemental observations conducted in 2022 and 2023 at five sites on the seafloor and two sites on land for the purpose of obtaining higher resolution of the subsurface structure, as well as previously acquired data from 26 sites in the northwestern Noto Peninsula in 2007 (Yoshimura et al., 2008).