Interplate slip before, during, and after the 2024 M w 7 Hyuga-nada earthquake, southwest Japan
2025-06-26
Using Global Navigation Satellite System data, we investigated the interplate slip before, during, and after the 2024 Hyuga-nada earthquake in Japan. Before the earthquake, a moment magnitude ( M w ) 6.0 slow-slip event (SSE) was observed from late 2023 in a downdip extension of the mainshock. The coseismic slip was adjacent to the 1996 Hyuga-nada earthquake source. The afterslip resolved near the hypocenter area and in the downdip extension of the mainshock, reaching M w 6.7 on 16 September 2024. Leading up to the earthquake, the recurrence interval for SSEs in the preslip area shortened from an average of 2 years, estimated from observations over the past 30 years, to 1 year, consistent with simulations in which the weakening of the Nankai megathrust was attributed to the cause.