M3.9 Earthquake near Atka, Alaska — 26 July 2026
A minor earthquake of magnitude 3.9 was recorded near Atka, Alaska on , with an epicentre 112 km southwest of Atka, at a focal depth of 35.0 km.
Time (UTC): 2026-07-26 17:16:12
Time (your timezone): —
Magnitude: 3.9 (minor)
Focal depth: 35.0 km (shallow)
Epicentre: 51.3761, -175.1460
Location: 112 km SW of Atka, Alaska
USGS link to NOAA tsunami information: Not linked
Review status: Reviewed
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 3.9 earthquake radiates roughly 11 tons of TNT equivalent in seismic energy.
The USGS assigns this earthquake a significance score of 234, 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 51.3761, -175.1460 — 112 km southwest of Atka. The closest other recorded event was a magnitude 2.2 earthquake 45 km west-northwest of here on 28 July 2026.
Why the 35 km depth matters
At 35 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 M3.9 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
52 further earthquakes have been recorded within about 150 km of the epicentre in the 6 days since this event, the largest of them magnitude 3.1.
111 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 6.2 event near Adak on 21 March 2025. This M3.9 event released about 2,818 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 2026 worldwide record. Browse the full monthly archive to compare periods.
Nearest recorded earthquakes to this epicentre
- M2.2 earthquake near Adak, Alaska — (45 km WNW)
- M2.1 earthquake near Adak, Alaska — (54 km W)
- M2.1 earthquake near Adak, Alaska — (55 km W)
- M2.4 earthquake near Adak, Alaska — (64 km SW)
- M2.1 earthquake near Adak, Alaska — (67 km W)
- M2.1 earthquake near Adak, Alaska — (72 km NNW)
- M2.2 earthquake near Adak, Alaska — (76 km WSW)
- M2.6 earthquake near Adak, Alaska — (89 km W)
- M1.1 earthquake near Adak, Alaska — (92 km NNW)
- M3.1 earthquake near Atka, Alaska — (93 km ENE)
Other magnitude 3 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 3.9 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 3.9 earthquake radiates roughly 11 tons of TNT equivalent in seismic energy.
How deep was the earthquake near Atka?
At 35 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 M3.9 earthquake near Atka 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 M3.9 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?
52 further earthquakes have been recorded within about 150 km of the epicentre in the 6 days since this event, the largest of them magnitude 3.1.
How often do earthquakes happen near Atka?
111 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 6.2 event near Adak on 21 March 2025. This M3.9 event released about 2,818 times less energy than that event.