The 2024 Noto earthquake and tsunami: insights from the static and adjoint state inversion methods

Abstract

In this study, we investigated the coseismic slip and deformation caused by the 2024 Mw 7.5 earthquake on the Noto Peninsula and the subsequent tsunami through both adjoint and static inversion modeling techniques. We leveraged a network of tsunami stations available across the Sea of Japan, along with detailed near-field geodetic data from GNSS stations and SAR-derived 3D deformation, to conduct these inversions. Our analyses generally revealed a significant slip zone northeast of the epicenter, corresponding to a deeper fault plane dipping 70º to the northwest. Notably, our adjoint inversion method successfully identified a landslide source in Toyama Bay, inferred directly from tsunami waveform data. This represents the first time a landslide source has been resolved by inverting water elevation data, highlighting the exceptional capability of the adjoint method in detecting non-seismic tsunami sources. The use of both modeling techniques not only enhanced our understanding of seismic events in this geologically complex region but also demonstrated the critical role of integrated geodetic and water elevation data for improving tsunami modeling and hazard assessment.