Coseismic Deep-Seated Gravitational Slope Deformations Triggered by the 2024 Mw 7.5 Noto Peninsula Earthquake

Abstract In the 2024 Noto Peninsula earthquake (Mw 7.5), many short and intermittent deformations were observed in the mountainous area of the peninsula. We conducted a differential analysis based on pre- and postearthquake digital elevation models and field surveys at two sites where particularly prominent deformations occurred in the northeastern peninsula. Our results determined the compression of the river plain and the extensional scarps on the back slopes, causing deep-seated gravitational slope deformation (DSGSD). These extensional scarps occurred along pre-existing DSGSD features, such as linear depressions and uphill-facing scarps, implying repeated growth. The Noto Peninsula has been repeatedly struck by large earthquakes, as evidenced by historical records and Pleistocene and Holocene marine terraces along the northern peninsular coast. The Noto Peninsula may be hiding multiple DSGSD features, but the DSGSD features we discovered have high potential as targets for off-fault paleoseismology research to help reconstruct the history of large earthquake events on the peninsula.