Source Process Estimation for the 2024 M _w 7.1 Hyuganada, Japan, Earthquake and Forward Modeling Using N‐net Ocean Bottom Seismometer Data

Abstract The source process of the 2024 M w 7.1 Hyuganada, Japan, earthquake was investigated using waveform inversion of the onshore strong motion records obtained from the region west of the source area. The main fault rupture occurred 6–12 km south of the hypocenter, with a maximum slip of 4.2 m. The rupture propagated unilaterally in the southern direction and stopped after approximately 12 s. Before and after the mainshock, low seismic activities were detected in the main‐slip region. The rate of slow slip events was lower in the main‐slip region than in the peripheral region, indicating that the main‐slip region was more strongly coupled than the peripheral region before the mainshock. The N‐net seafloor seismograms of the mainshock with a frequency of ∼0.05 Hz recorded east of the source area were reproduced for several stations using the empirical Green's function approach based on the estimated source process data.