M5.1 Earthquake in the Volcano Islands, Japan region — July 9, 2023

On July 9, 2023 at 18:49 UTC, a magnitude 5.1 shallow crustal earthquake struck in the Volcano Islands, Japan region, at a depth of 10.0 km and coordinates 24.0081°, 143.0829°. This earthquake was detected by 133 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 400, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 5.1 releases seismic energy equivalent to roughly 674 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 2.0 km — a useful intuition for the size of the slip patch on the fault.

This earthquake is part of an ongoing aftershock sequence following the magnitude 5.3 mainshock that occurred 1 day ago in the Volcano Islands, Japan region. Since the mainshock, the USGS has recorded 0 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.

The epicenter is located in Japan, a region characterized by the intersection of four tectonic plates — Pacific, Philippine Sea, Eurasian, and North American — creating multiple subduction zones. The nearest mapped fault system is the Japan Trench. View all earthquakes in Japan.

Learn more: Magnitude scale · Aftershock sequences