Earthquake in Southwestern Nagasaki Prefecture on July 25
On July 25, 2025, at 11:17 a.m., an M4.8 earthquake occurred in southwestern Nagasaki Prefecture at a depth of 9 km (maximum seismic intensity 4). This event occurred within the crust, featuring a north-south oriented tension axis. The following day, on July 26 at 12:28 a.m., another earthquake of M3.4 (depth of 8 km and maximum seismic intensity 2) occurred in nearly the same location.
A review of seismic activity since October 2000 reveals that three earthquakes of M4.0 or greater have occurred near the epicenter (Area a). This includes an M4.2 earthquake on April 19, 2017 (depth: 16 km, maximum seismic intensity 3) and an M4.3 earthquake on June 9 of the same year (depth: 16 km, maximum intensity 4).
A review of seismic activity since 1919 reveals that 12 earthquakes of M5.0 or greater have occurred near the epicenter (Area b). Notably, an M5.7 earthquake on August 6, 1984, resulted in damage to 53 buildings in Obama Town, Nagasaki Prefecture (now Unzen City). Additionally, on December 8, 1922, two large earthquakes with M6.9 and M6.5 occurred in Nagasaki Prefecture, leading to 26 fatalities, 39 injuries, and the complete destruction of 195 residential buildings.
(according to data from the "Materials for Comprehensive List of Destructive Earthquakes in Japan").
Japan Meteorological Agency
[Evaluation of Seismic Activities for July 2025 (August 12, 2025)]