Rupture process of the 2024 Noto Peninsula earthquake inferred from strong motion, teleseismic, and geodetic data

We performed joint source inversions of strong motion, teleseismic, and geodetic data to investigate the rupture process of the 2024 Noto Peninsula earthquake. A multi-segment fault model was constructed based on the distribution of relocated aftershocks and survey results of submarine active faults. The hypocenter was located on a secondary fault subparallel to the main fault system, where preceding swarm activity had occurred. According to the inversion results, the rupture initially propagated northwestward up-dip along the secondary fault and, after approximately 6 s, migrated onto the main fault system. Moderate slips then occurred around the migration point. Subsequently, the rupture propagated bilaterally, with large slips occurring simultaneously in the northwestern part of the Noto Peninsula and the northeastern offshore region. In the latter region, both southeast- and northwest-dipping faults ruptured. Large slips were primarily obtained at depths shallower than approximately 8.5 km, where relatively few aftershocks occurred. Our results suggested that rupture termination at both the northeastern and southwestern ends of the fault was possibly controlled by fault geometry. The intensive swarm activity before the earthquake likely influenced the rupture process. The rupture primarily occurred in segments along known submarine active faults with large slips, highlighting the importance of submarine fault information for assessing future coastal earthquakes.