M4.1 Earthquake near Anamizu, Japan — 31 July 2025
A light earthquake of magnitude 4.1 was recorded near Anamizu, Japan on , with an epicentre 253 km west-northwest of Anamizu, at a focal depth of 420.7 km.
Time (UTC): 2025-07-31 00:00:35
Time (your timezone): —
Magnitude: 4.1 (light)
Focal depth: 420.7 km (deep)
Epicentre: 38.2759, 134.3430
Location: 253 km WNW of Anamizu, 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 4.1 earthquake radiates roughly 21 tons of TNT equivalent in seismic energy.
The USGS assigns this earthquake a significance score of 259, 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 38.2759, 134.3430 — 253 km west-northwest of Anamizu. The closest other recorded event was a magnitude 4.0 earthquake 16 km southwest of here on 24 October 2025.
Why the 421 km depth matters
At 421 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 M4.1 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 421 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.
11 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 4.8 event near Hakui on 20 February 2025. This M4.1 event released about 11 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 July 2025 worldwide record. Browse the full monthly archive to compare periods.
Nearest recorded earthquakes to this epicentre
- M4.0 earthquake near Ama, Japan — (16 km SW)
- M4.0 earthquake near Ama, Japan — (28 km W)
- M4.0 earthquake near Anamizu, Japan — (53 km SSE)
- M4.4 earthquake near Ama, Japan — (76 km WNW)
- M4.1 earthquake near Ama, Japan — (89 km WNW)
- M4.0 earthquake near Mikuni, Japan — (107 km SSE)
- M4.3 earthquake near Mikuni, Japan — (108 km SSE)
- M4.0 earthquake near Mikuni, Japan — (142 km SSE)
- M4.1 earthquake near Kameshima, Japan — (164 km SSE)
- M4.1 earthquake near Mikuni, Japan — (180 km SSE)
Other magnitude 4 earthquakes worldwide
- M4.3 earthquake near Puerto Madero, Mexico —
- 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 —
- M4.3 earthquake near Orosi, Costa Rica —
- M4.1 earthquake near Masohi, Indonesia —
- M4.1 earthquake near Yamada, Japan —
- M4.3 earthquake near El Arenal, Mexico —
Questions about this earthquake
How strong is a magnitude 4.1 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 4.1 earthquake radiates roughly 21 tons of TNT equivalent in seismic energy.
How deep was the earthquake near Anamizu?
At 421 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 M4.1 earthquake near Anamizu 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 M4.1 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 421 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 Anamizu?
11 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 4.8 event near Hakui on 20 February 2025. This M4.1 event released about 11 times less energy than that event.