Finite-fault Slip Distribution and Initial Water Elevation of the 2024 Noto Peninsula, Japan Earthquake Estimated from Tsunami Waveforms

On January 1, 2024, a moment magnitude (Mw) 7.5 earthquake struck the Noto Peninsula area in Japan, triggering a tsunami and causing significant casualties and massive economic and property damage. Many wave gauges around the Sea of Japan recorded the tsunami. In this study we inverted the observed tsunami waveforms for the distributed slip on the JSPJ (Japan Sea Earthquake and Tsunami Research Project) fault model, and the initial water elevation, respectively. The results show that the earthquake's slip distribution concentrates mainly on the NT4 subfault located to the northeast of the peninsula, with the maximum slip reaching about 5m. This slip model results in a maximum initial tsunami wave height that reaches similar to 3m. The inversion of initial water elevation indicates a main tsunami source roughly located in 137.3 degrees E-137.6 degrees E and 37.5 degrees N-37.8 degrees N, with the maximum initial elevation of 2.7m, which is consistent with the finite-fault inversion. We also simulated the tsunami waveforms at observation stations using the inverted JSPJ fault model and the initial water elevation to evaluate the effects of wave dispersion. The results indicate that the effects of dispersion were minor at most stations, and only observable at far-field stations along the eastern Russian coast and the western coast of Hokkaido.