An analysis of the pre-, co-, and post-seismic effects of the 2024 Noto Earthquake and Tsunami

Saeed Y. Mohanna, Lingsen Meng, Alessandro Vuan, Tung-Cheng Ho, Chao An, & Liuwei Xu

Published September 8, 2024, SCEC Contribution #13530, 2024 SCEC Annual Meeting Poster #008

With 299 fatalities, the 2024 New Year’s Day earthquake and subsequent tsunami that struck the Noto Peninsula was the deadliest since the 2011 Tohoku earthquake and tsunami. To understand the physical driver of this earthquake, we analyzed the spatiotemporal evolution of seismicity one month before and after the earthquake. We used the EQTM template matching and GrowClust software to detect and relocate earthquakes, respectively. We detected ~138k events, ~7 times more than those in the Japanese Meteorological Agency’s catalog. Our preliminary analysis of earthquake migration speeds shows signs of both fluid diffusion and aseismic slip. We plan to further refine our study by overlapping the seismicity of the enhanced catalog to 3-D velocity models to understand the geologic influences on pore fluid pressure increases before the earthquake. We also investigated the coseismic slip and deformation, using both adjoint and static inversion modeling techniques. To perform these inversions, we capitalized on the extensive network of tsunami stations available across the Sea of Japan, combined with detailed near-field geodetic data from GNSS stations and 3-D deformation data derived from synthetic aperture radar data, to perform these inversions. Our analyses consistently identified a region of significant slip located northeast of the epicenter, corresponding to a deeper fault plane that dips toward the northwest. Notably, the results from our adjoint inversion method successfully pinpointed a landslide source in Toyama Bay, directly inferred from tsunami waveform data. This landmark achievement marks the first instance of resolving a landslide source from water elevation data with this inversion method, underscoring the exceptional capability of the adjoint method in detecting non-seismic tsunami sources. Both modeling techniques improved our understanding of seismic events in this geologically complex region highlighting the crucial role of integrating geodetic and water elevation data to enhance tsunami modeling and hazard assessment.

Key Words
Noto earthquake and tsunami, static inversion, adjoint inversion, seismicity analyses

Citation
Mohanna, S. Y., Meng, L., Vuan, A., Ho, T., An, C., & Xu, L. (2024, 09). An analysis of the pre-, co-, and post-seismic effects of the 2024 Noto Earthquake and Tsunami. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology