M4.0 Earthquake near Bonin Islands, Japan region — 21 April 2025
A light earthquake of magnitude 4.0 was recorded near Bonin Islands, Japan region on , at a focal depth of 431.1 km.
Time (UTC): 2025-04-21 16:14:46
Time (your timezone): —
Magnitude: 4.0 (light)
Focal depth: 431.1 km (deep)
Epicentre: 26.4846, 140.5490
Location: Bonin Islands, Japan region
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 26.4846, 140.5490. The closest other recorded event was a magnitude 4.7 earthquake 11 km north-northwest of here on 04 September 2025.
Why the 431 km depth matters
At 431 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 431 km focal depth is too great to deform the sea floor significantly. 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.
38 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.5 event near Bonin Islands on 13 May 2025. This M4.0 event released about 178 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 April 2025 worldwide record. Browse the full monthly archive to compare periods.
Nearest recorded earthquakes to this epicentre
- M4.7 earthquake near Bonin Islands, Japan region — (11 km NNW)
- M4.3 earthquake near Bonin Islands, Japan region — (24 km ESE)
- M4.5 earthquake near Bonin Islands, Japan region — (58 km ESE)
- M4.3 earthquake near Bonin Islands, Japan region — (72 km NNW)
- M4.1 earthquake near Bonin Islands, Japan region — (80 km NNW)
- M4.3 earthquake near Bonin Islands, Japan region — (83 km NNW)
- M4.1 earthquake near Bonin Islands, Japan region — (86 km NNW)
- M4.1 earthquake near Bonin Islands, Japan region — (86 km NNW)
- M4.5 earthquake near Bonin Islands, Japan region — (86 km NNW)
- M4.0 earthquake near Bonin Islands, Japan region — (94 km NNW)
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 Bonin Islands?
At 431 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 Bonin Islands 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 431 km focal depth is too great to deform the sea floor significantly. 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 Bonin Islands?
38 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.5 event near Bonin Islands on 13 May 2025. This M4.0 event released about 178 times less energy than that event.