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

[U15-P46] Marine Earth Science Studies on the 2024 Noto Earthquake (M7.6) by R/V Hakuho-maru

*Jin-Oh Park¹, Asuka Yamaguchi¹, Chiori Tamura¹, Katsura Kameo¹, Hideo Ishigaki¹, YUE SUN¹, Yuqi Lyu¹, Noboru Yamakawa¹, Jumpei Yoshioka¹, Seitaro Ono¹, Yuning Zeng¹, Ayanori Misawa², Tetsuo No³, Kusumoto Satoshi³, Hironori Otsuka⁴, Atsushi Matsuoka⁵, Rina Fukuchi⁶, Takuya Sagawa⁷, Yoichi Usui⁷, Taro Arikawa⁸, Takanori Kagoshima⁹, JING ZHANG⁹, Shimpei Ohtsuka⁹, Michael Julian Haryanto⁹, Tomohiro Toki¹⁰, Takahisa Maekura¹⁰, Zahra Zandvakili¹¹, Yudai Kobayashi¹², Tomoharu Senjyu¹³, Akie Sakai¹³, Yoshiki Horiuchi¹⁴, Hikaru Iwamaru¹⁴, Yusuke Sato¹⁵, Yu Suzuki¹⁶ (1.AORI, 2.AIST, 3.JAMSTEC, 4.KOBEC, 5.Niigata University, 6.Naruto University of Education, 7.Kanazawa University, 8.Chuo University, 9.University of Toyama, 10.University of the Ryukyus, 11.Kochi University, 12.Kobe University, 13.Kyushu University, 14.NME, 15.MWJ, 16.MOLMEC)

Keywords:Noto earthquake, submarine active fault, tsunami, marine environment

On January 1, 2024, a large earthquake (M7.6) and the accompanying tsunami caused extensive damage in and around the Noto Peninsula. The 2024 Noto Earthquake (M7.6) exhibited a reverse fault-type focal mechanism with a pressure axis in the northwest-southeast direction (Japan Meteorological Agency, 2024), and the possibility of reactivation of a pre-existing active fault has been pointed out. The earthquake source fault estimated from the aftershock distribution of the January 2024 earthquake (Japan Meteorological Agency, 2024) has a total length of approximately 150 km from the west coast of the Noto Peninsula to the northeast offshore the Noto Peninsula. It is inferred that part of the ~150-km-long fault, as an active submarine fault, could serve as the source of the tsunami in the northeast offshore the Noto Peninsula. However, the structure and physical properties of submarine active faults with a maximum slip of about 4 m (Satake, 2024), which are believed to have caused tsunamis, are still unknown. Moreover, knowledge about the marine environment in the earthquake rupture area is extremely lacking.
To investigate the Noto Earthquake (M7.6) and the impact of earthquakes and tsunamis on the marine environment and marine ecosystem, we conducted a multidisciplinary survey (cruise ID: KH-24-E1) by using the academic research vessel "Hakuho-maru" in the earthquake rupture area offshore the northeast coast of the Noto Peninsula from March 4 to 16, 2024 (13 days): (1) Multi-channel seismic reflection profiling to obtain shallow crustal images of the earthquake source fault; (2) Sub-bottom (3.5 kHz) profiling to obtain high-resolution subsurface structure; (3) Multi-beam echo sounder (MBES) survey to obtain precise seafloor topography; (4) Sediment sampling by piston corer; (5) Sediment sampling, underwater camera observation, and heat flow measurement by multiple corer system; (6) CTD measurement and bottom water sampling; (7) gravity observation by onboard gravimeter; (8) Seafloor observation by underwater drone and deep sea camera equipped by dredge sampler; (9) Current observations by lowered acoustic Doppler current profiler and mooring system; and (10) Aerosol sampling. In this talk, we are going to present preliminary results of all the observations conducted during the cruise.