Publication of report – A Multiplex Rupture Sequence Under Complex Fault Network Due To Preceding Earthquake Swarms During the 2024 Mw 7.5 Noto Peninsula, Japan, Earthquake

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At approximately 16:10 on January 1, 2024, a major earthquake with a magnitude (Mw) of 7.5, the “2024 Noto Peninsula Earthquake” (hereinafter referred to as the “Noto Peninsula Earthquake”), occurred in the Noto region of Ishikawa Prefecture. The maximum seismic intensity was recorded at 7, resulting in extensive damage, including many casualties. The existence of multiple active faults, mainly extending in a northeast-southwest direction, was known in the Noto Peninsula and its surrounding areas. Slow non-seismic crustal deformation and active seismic activity, thought to be related to fluid movement in the subsurface, had been observed since about three years ago. Clarifying how these networks of active faults and crustal activity drive the rupture of large earthquakes is important for understanding the mechanism of earthquake generation and the generation of strong shaking.

A report that has been published by the research group led by Prof. Yukitoshi Fukahata, Disaster Prevention Research Institute (DPRI), Kyoto University; and Assistant Prof. Ryo Okuwaki, University of Tsukuba, analyzed seismic waveform data observed around the world to estimate the rupture process of the Noto Peninsula earthquake. As a result, it was found that this earthquake consisted of multiple rupture episodes, and in particular, the initial rupture, which lasted about 10 seconds from the onset of the earthquake, overlapped with an area of ​​active crustal activity that had been observed before the earthquake.

The results of this study were published online in the international academic journal “Geophysical Research Letters” on June 8, 2024.