On January 1, 2024, a large shock of M7.5 occurred on the Noto peninsula in Japan. This mammoth quake left millions of square miles severely impacted throughout the region, mostly thanks to an immense amount of vertical lift. Ryosuke Ando, an associate professor at the University of Tokyo’s Graduate School of Science, led a cutting-edge study. His hope was to see what the dynamics were with this earthquake. An article detailing the findings was recently published in the journal Earth, Planets and Space.
The earthquake caused different amounts of uplift over the entire area affected by the rupture. In places, the ground surface was lifted as much as 1 to 2 meters. Other areas experienced an alarming rise of up to 5 meters. The considerable spatial variability in uplift led Wheeler and colleagues to query what was causing this pattern. Intrigued, Ando and his research team set out to investigate the mechanisms responsible.
Faults and Uplift Mechanisms
The research also determined three widespread fractures that eased the occurrence of the 2024 Noto Peninsula earthquake. Two of these faults, the Monzen Fault and the Noto Peninsula Hoku-gan Fault Zones, dip to the southeast similar as the subducting plate. By comparison, the Toyama Trough Sei-en Fault has a northwest dip. These investigations detected marks of seafloor active faults extending along the northern offshore area of the Noto Peninsula.
The major uplift seen during the M7.8 earthquake is due to the complex interaction of all four of these faults. Ando explained, “During the Noto Peninsula earthquake, we saw devastating uplift in some areas compared to others. In this study, we set out to understand the mechanism controlling the magnitude and spatial and temporal variation of fault slip and the resulting ground surface uplift.”
What’s more, the region had been under the influence of a long-term pattern of smaller seismic activity prior to the big shake. The unusual, local seismic swarm indicated heightened geologic activity. This indicates that the region is preparing for a more substantial release of tectonic stress.
Advanced Simulation Techniques
To untangle the intricacies of fault behavior throughout the quake, scientists turned to sophisticated supercomputer simulations. We modeled the simulations based on observational data from the fault shape. This methodology allowed us to study qualitatively and quantitatively how non-planar faults affect the seismic process.
Ando noted, “Our simulation with a supercomputer enabled the analysis of the three-dimensional fault geometry, which is irregularly shaped. We revealed that the fault geometry controlled the overall process through the relative fault orientations to the compressional force acting in the tectonic plate in this region.”
Using these simulations, Ando and his research team were able to recreate the difference in uplift felt during that same earthquake. The study’s results point to the need to prioritize understanding fault geometries when analyzing earthquake hazards.
Implications for Future Earthquake Preparedness
This research is not merely of academic interest. It has huge ramifications for how we save lives from future earthquakes and identify risk moving forward. McLaren-Ando underscored this idea. He said, “We’ve paved the way for constraining the characteristics of a future fault slip pattern, ahead of large earthquakes, by demonstrating the power of simulations using detailed models of fault geometries. We hope this new finding will lead us to create an innovative approach. This approach will be used to evaluate the intensity and impacts of hazards resulting from major future earthquakes.
Whether a tsunami or an earthquake, seismic events are still being studied and understood by scientists and researchers. Research such as Ando’s provides invaluable guidance that enables communities to better prepare for and respond to earthquakes. Understanding fault behavior and uplift patterns may enhance disaster response strategies and infrastructure resilience in regions prone to seismic activity.