M3.1 Earthquake near Kobuk, Alaska — 16 September 2025
A minor earthquake of magnitude 3.1 was recorded near Kobuk, Alaska on , with an epicentre 50 km north of Kobuk, at a focal depth of 0.0 km.
Time (UTC): 2025-09-16 01:12:31
Time (your timezone): —
Magnitude: 3.1 (minor)
Focal depth: 0.0 km (shallow)
Epicentre: 67.3530, -156.6610
Location: 50 km N of Kobuk, Alaska
USGS link to NOAA tsunami information: Not linked
Review status: Automatic
Source: USGS event page
How strong was this earthquake?
Minor earthquakes in this range are felt by people close to the epicentre as a brief jolt or rattle, but they very rarely cause any damage.
A magnitude 3.1 earthquake radiates roughly 674 kg of TNT equivalent in seismic energy.
The USGS assigns this earthquake a significance score of 148, 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 67.3530, -156.6610 — 50 km north of Kobuk. The closest other recorded event was a magnitude 1.7 earthquake 0 km south of here on 15 September 2025.
Why the 0 km depth matters
At 0 km this was a shallow earthquake. Shallow events release their energy close to the surface, so for a given magnitude they produce noticeably stronger shaking — and more damage — than deeper ones. Roughly three quarters of all earthquakes worldwide occur at shallow depths.
This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size may be noticed locally, especially close to the epicentre. Its shallow focus makes stronger surface shaking more likely than for a deeper event of the same magnitude.
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 M3.1 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; 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
8 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 2.9.
2 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 Ambler on 13 March 2025. This M3.1 event released about 1000 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 September 2025 worldwide record. Browse the full monthly archive to compare periods.
Nearest recorded earthquakes to this epicentre
- M1.7 earthquake near Kobuk, Alaska — (0 km S)
- M1.8 earthquake near Kobuk, Alaska — (0 km S)
- M2.0 earthquake near Kobuk, Alaska — (1 km WSW)
- M2.0 earthquake near Kobuk, Alaska — (1 km S)
- M2.6 earthquake near Kobuk, Alaska — (4 km SSW)
- M2.5 earthquake near Kobuk, Alaska — (4 km WNW)
- M1.7 earthquake near Kobuk, Alaska — (6 km WNW)
- M3.0 earthquake near Kobuk, Alaska — (6 km ENE)
- M1.5 earthquake near Kobuk, Alaska — (10 km W)
- M3.5 earthquake near Kobuk, Alaska — (15 km E)
Other magnitude 3 earthquakes worldwide
- M3.4 earthquake near Charlotte Amalie, U.S. Virgin Islands —
- M3.0 earthquake near Charlotte Amalie, U.S. Virgin Islands —
- M3.3 earthquake near Desert Hot Springs, CA —
- M3.3 earthquake near Suárez, Puerto Rico —
- M3.3 earthquake near Charlotte Amalie, U.S. Virgin Islands —
- M3.0 earthquake near Palomar Observatory, CA —
- M2.9 earthquake near Gilroy, CA —
- M3.1 earthquake near Miramichi, Canada —
Questions about this earthquake
How strong is a magnitude 3.1 earthquake?
Minor earthquakes in this range are felt by people close to the epicentre as a brief jolt or rattle, but they very rarely cause any damage. A magnitude 3.1 earthquake radiates roughly 674 kg of TNT equivalent in seismic energy.
How deep was the earthquake near Kobuk?
At 0 km this was a shallow earthquake. Shallow events release their energy close to the surface, so for a given magnitude they produce noticeably stronger shaking — and more damage — than deeper ones. Roughly three quarters of all earthquakes worldwide occur at shallow depths.
Was the M3.1 earthquake near Kobuk 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 may be noticed locally, especially close to the epicentre. Its shallow focus makes stronger surface shaking more likely than for a deeper event of the same magnitude.
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 M3.1 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; 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?
8 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 2.9.
How often do earthquakes happen near Kobuk?
2 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 Ambler on 13 March 2025. This M3.1 event released about 1000 times less energy than that event.