Noto Peninsula EQ

We published a new paper in Earth, Planets and Space about the aftershock distribution of the Mj7.6 Noto Peninsula earthquake on 1 January 2024.

This earthquake triggered extensive aftershocks. Previously, offshore aftershock locations were poorly constrained due to simplified velocity models. Our study used a 3D velocity model and Markov chain Monte Carlo to precisely determine hypocenters. Results show aftershocks occurred at 15 km depth or shallower, indicating the main rupture involved shallow submarine faults, contributing to tsunami generation. The aftershock distribution significantly differs from previous seismicity, suggesting a complex fault network across the peninsula influenced the Mj7.6 earthquake and subsequent activity, as suggested in Sawaki et al. (2025) .

Check the paper below for details!

• Shiina, T., H. Horikawa, Y. Sawaki, K. Sagae, and K. Imanishi (2025). Aftershock distribution of the 2024 Noto Peninsula Earthquake, Japan, determined using a 3D velocity structure and uncertainty quantification. Earth, Planets and Space, 77, 94. doi: 10.1186/s40623-025-02227-4 (Open Access)

We have estimated the fault geometry of the 2024 Noto Peninsula Earthquake in central Japan on 1 January 2024. Our analysis reveals major and minor fault planes aligned along the coastline beneath the peninsula. Notably, we identified a more counter-clockwise rotated plane in eastern Wajima and an east-dipping plane along the west coast. These localized structural complexities suggest intricate fault slip behavior and exhibit a strong correlation with gravity anomalies and geological structures. This research contributes to a deeper understanding of the formation and seismotectonics of the Noto Peninsula.

We also won the AIST President Award 2024 related to Contribution to National Earthquake Disaster Prevention Measures: Response to the 2024 Noto Peninsula Earthquake (in Japanese)!

Check the paper and software below!

• Sawaki, Y., T. Shiina, K. Sagae, Y. Sato, H. Horikawa, A. Miyakawa, K. Imanishi, and T. Uchide (2025). Fault Geometries of the 2024 Mw 7.5 Noto Peninsula Earthquake from Hypocenter-Based Hierarchical Clustering of Point-Cloud Normal Vectors. Journal of Geophysical Research: Solid Earth, 130, e2024JB030233. doi: 10.1029/2024JB030233 (Open Access)
• Sawaki, Y., Y. Sato, and T. Uchide (2025). FaultNVC: Earthquake Fault Plane Extractor through Point-Cloud Normal Vector Clustering for Hypocenter Distributions [Software]. Open-File Report of Geological Survey of Japan, AIST, no. 759. https://www.gsj.jp/publications/pub/openfile/openfile0759.html

I visited Noto Peninsula in central Japan, where M7.6 earthquake occurred on 1 Jan 2024. I saw the great uplift on the western coast and surface rupture in the eastern area.