M4.0 Earthquake near Mikuni, Japan — 26 August 2025
A light earthquake of magnitude 4.0 was recorded near Mikuni, Japan on , with an epicentre 173 km northwest of Mikuni, at a focal depth of 364.5 km.
Time (UTC): 2025-08-26 22:20:46
Time (your timezone): —
Magnitude: 4.0 (light)
Focal depth: 364.5 km (deep)
Epicentre: 37.4298, 134.9170
Location: 173 km NW of Mikuni, Japan
USGS link to NOAA tsunami information: Not linked
Review status: Reviewed
Source: USGS event page
How strong was this earthquake?
Light earthquakes are widely felt near the epicentre and can rattle windows, dishes and hanging objects. Damage is uncommon and usually limited to cracked plaster or fallen loose items.
A magnitude 4.0 earthquake radiates roughly 15 tons of TNT equivalent in seismic energy.
The USGS assigns this earthquake a significance score of 246, which is below the USGS threshold of more than 600 for its significant-earthquake list. The ranking combines magnitude with available Did You Feel It responses and PAGER alert level; it is not a direct measurement of damage.
Where was the epicentre?
The epicentre was located at 37.4298, 134.9170 — 173 km northwest of Mikuni. The closest other recorded event was a magnitude 4.3 earthquake 31 km west-southwest of here on 23 January 2025.
Why the 364 km depth matters
At 364 km this was a deep-focus earthquake, occurring well inside the subducting slab rather than in the crust. Deep events are rarely damaging even at large magnitudes, though they can be felt over very long distances.
This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size is often felt across the surrounding area. Its deep focus normally weakens surface shaking while spreading perceptible motion over a broad area.
What does the tsunami information flag mean?
The USGS record does not carry a link to NOAA tsunami information. That field is not an all-clear and does not state whether a tsunami occurred. In this case, a damaging tsunami would be less likely because at M4.0 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 364 km focal depth is too great to deform the sea floor significantly; it occurred inland rather than beneath the sea floor. For an active coastal alert, use tsunami.gov or your local warning authority.
How earthquakes generate tsunamis, and what the alert levels mean →
Aftershocks and local seismic history
No further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event.
18 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.1 event near Hakui on 14 December 2025. This M4.0 event released about 45 times less energy than that event.
How long aftershock sequences last, and how large they get →
Where this event sits in the record
This earthquake is part of the August 2025 worldwide record. Browse the full monthly archive to compare periods.
Nearest recorded earthquakes to this epicentre
- M4.3 earthquake near Mikuni, Japan — (31 km WSW)
- M4.0 earthquake near Mikuni, Japan — (36 km SSE)
- M4.0 earthquake near Anamizu, Japan — (54 km NNW)
- M4.1 earthquake near Kameshima, Japan — (67 km S)
- M4.1 earthquake near Mikuni, Japan — (75 km SE)
- M4.0 earthquake near Ama, Japan — (106 km NW)
- M4.1 earthquake near Anamizu, Japan — (107 km NNW)
- M4.8 earthquake near Hakui, Japan — (111 km ESE)
- M4.0 earthquake near Ama, Japan — (118 km NW)
- M4.8 earthquake near Hakui, Japan — (138 km ESE)
Other magnitude 4 earthquakes worldwide
- M4.1 earthquake near Charlotte Amalie, U.S. Virgin Islands —
- M4.0 earthquake near Charlotte Amalie, U.S. Virgin Islands —
- M4.2 earthquake near Banda Sea —
- M3.8 earthquake near Cloverdale, CA —
- M3.8 earthquake near Geyserville, California —
- M4.1 earthquake near Masohi, Indonesia —
- M4.1 earthquake near Yamada, Japan —
- M3.8 earthquake near Atka, Alaska —
Questions about this earthquake
How strong is a magnitude 4.0 earthquake?
Light earthquakes are widely felt near the epicentre and can rattle windows, dishes and hanging objects. Damage is uncommon and usually limited to cracked plaster or fallen loose items. A magnitude 4.0 earthquake radiates roughly 15 tons of TNT equivalent in seismic energy.
How deep was the earthquake near Mikuni?
At 364 km this was a deep-focus earthquake, occurring well inside the subducting slab rather than in the crust. Deep events are rarely damaging even at large magnitudes, though they can be felt over very long distances.
Was the M4.0 earthquake near Mikuni felt?
This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size is often felt across the surrounding area. Its deep focus normally weakens surface shaking while spreading perceptible motion over a broad area.
What does the USGS tsunami field mean for this event?
The USGS record does not carry a link to NOAA tsunami information. That field is not an all-clear and does not state whether a tsunami occurred. In this case, a damaging tsunami would be less likely because at M4.0 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 364 km focal depth is too great to deform the sea floor significantly; it occurred inland rather than beneath the sea floor. For an active coastal alert, use tsunami.gov or your local warning authority.
Have there been aftershocks?
No further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event.
How often do earthquakes happen near Mikuni?
18 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.1 event near Hakui on 14 December 2025. This M4.0 event released about 45 times less energy than that event.