Scientists Uncover Fault Geometry Behind the 2024 Noto Peninsula Earthquake in Japan

On January 1, 2024, a massive 7.5-magnitude earthquake struck Japan’s Noto Peninsula, causing widespread damage as the ground dramatically rose. This earthquake resulted in ground uplift, with some areas experiencing a rise of up to 5 meters (16.4 feet). A research team led by Ryosuke Ando from the University of Tokyo has now revealed that the earthquake’s irregular fault geometry played a significant role in the extent and distribution of the uplift. The team’s groundbreaking study, recently published in Earth, Planets and Space, provides new insights into the earthquake’s causes and its effects on the region.

Earthquake’s Impact and Fault Geometry

The 2024 earthquake was caused by three major conjugate faults, which are faults with opposite lateral movements. Two of these faults, the Monzen Fault and the Noto Peninsula Hoku-gan Fault Zones, dipped southeast, while the third, the Toyama Trough Sei-en Fault, dipped northwest. Using advanced 3D simulations, the researchers were able to analyze the way the faults’ geometry, angles, and orientation affected seismic activity.

The findings of the study suggest that the earthquake’s irregular fault structure was a critical factor in the varying levels of uplift across the region. The fault segments that were perpendicular to the compressional forces in the tectonic plate experienced the most significant slip. This resulted in dramatic ground uplift in certain areas of the peninsula. The team’s simulations showed that vertical displacement was especially concentrated around fault traces, where the faults deviated from their usual horizontal alignment.

Supercomputer Simulations Reveal Ground Uplift Patterns

To understand the cause of the earthquake’s impact, the research team used supercomputers to simulate the fault activity and its effects on the surrounding area. Their simulations closely matched the observed uplift patterns, providing strong evidence for the role of the fault geometry in determining the earthquake’s devastating impact.

The Noto Peninsula had experienced a series of smaller, shallow earthquakes leading up to the January 1st event. These tremors provided crucial data on the stress conditions and the fault’s behavior, which were incorporated into the team’s models. By combining this historical data with advanced simulations, the researchers were able to better predict the areas most at risk of ground displacement.

Importance of Fault Geometry in Earthquake Prediction

Ryosuke Ando, the lead researcher of the study, highlighted the critical role of fault geometry in understanding earthquake behavior. “Our simulations revealed that the irregular 3D fault geometry controlled the rupture process and uplift patterns,” he explained. According to Ando, the study’s findings could have a profound impact on how scientists model future earthquakes, especially in tectonically active regions like Japan.

Incorporating fault geometry into dynamic rupture scenarios allows scientists to create more accurate predictions of earthquake behavior. This improved understanding can help in the development of more effective risk reduction strategies and better hazard assessments, potentially saving lives and minimizing damage in future seismic events.

Ongoing Research and Future Implications

The results of this study highlight the importance of ongoing research into earthquake dynamics and fault structures. Understanding the precise mechanisms behind earthquakes is essential for improving early warning systems and disaster preparedness. Advanced simulations, such as those used in this study, could be key to creating more reliable earthquake forecasts in the future.

The research was supported by several prestigious organizations, including the Japan Society for the Promotion of Science, the Ministry of Education, Culture, Sports, Science, and Technology, and the Japan Agency for Marine-Earth Science and Technology. These institutions are committed to advancing scientific knowledge and improving disaster preparedness in earthquake-prone regions.

The Path Forward

This groundbreaking study is a significant step toward understanding the complex dynamics of earthquakes and their effects on the Earth’s surface. As the research community continues to refine its models, the hope is that future earthquakes can be predicted with greater accuracy, leading to better-prepared communities and improved disaster response strategies.