M3.9 earthquake – Nikolski, Alaska
A magnitude 3.9 earthquake struck in the Nikolski, Alaska region at 08:28 UTC on 16 Sept 2026, at a depth of 91 km, according to USGS.
Data: USGS · updated 2026-09-16 15:43 UTC · reviewed
- Magnitude
- 3.9minor
local magnitude (Richter) (ml) - Depth
- 90.5 km
- Status
- Reviewed
- Origin time
- 2026-09-16 08:28:51 UTC
- Epicentre
- 52.374° N, 171.157° W
Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map
Nearby places
| Place | Distance | Est. shaking |
|---|---|---|
| No towns within 400 km. This is a remote area. | ||
Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more.
Every agency's solution
Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · AK, which has been reviewed by an analyst.
| Agency | Magnitude | Depth | Epicentre | Time offset | Status |
|---|---|---|---|---|---|
| USGS · AKheadlineAlaska Earthquake Center via U.S. Geological Survey | 3.9 ml | 90.5 km | 52.37° N, 171.16° W | – | Reviewed |
How big was it?
Often felt by people at rest close to the epicentre, rarely causes damage.
It released roughly the energy of 11 t of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 91 km this was a intermediate-depth earthquake, which spreads shaking over a wider area but less intensely.
M3.9 releases about 32× the energy of M2.9, and its waves are about 10× taller on a seismogram. Energy: 11 t of TNT vs 338 kg of TNT.
Each square is the energy of one M2.9. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
10 later earthquakes within 30 km; the largest was M3.9 6 days ago. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M3.9
10 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 34.64 | 3.1 | 100 |
| 45.25 | 3.8 | 105 |
| 46.25 | 2.8 | 102 |
| 62.64 | 3.2 | 99 |
| 90.82 | 3.2 | 97 |
| 92.56 | 3.7 | 111 |
| 109.32 | 2.9 | 97 |
| 111.24 | 3.1 | 51 |
| 121.52 | 3.6 | 106 |
| 136.26 | 3.9 | 129 |
- 3.9Nikolski, Alaska09-22 00:44
- 3.8Nikolski, Alaska09-18 05:43
- 3.7Nikolski, Alaska09-20 05:02
- 3.6Nikolski, Alaska09-21 10:00
- 3.2Nikolski, Alaska09-18 23:07
- 3.2Nikolski, Alaska09-20 03:18
- 3.1Nikolski, Alaska09-17 19:07
- 3.1Nikolski, Alaska09-20 23:43
- 2.9Nikolski, Alaska09-20 21:48
- 2.8Nikolski, Alaska09-18 06:43
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports on SeismoAtlas
No reports yet.
Event id aka2026sjepok. First recorded here 28 Sept 2026, 17:32:11 UTC. Solutions: USGS · AK (usgs:aka2026sjepok). Cite as: SeismoAtlas, “M3.9 earthquake – Nikolski, Alaska”, https://seismoatlas.com/earthquake/aka2026sjepok-m3-9-earthquake-nikolski-alaska, data from USGS.
JSON: /api/v1/events/aka2026sjepok. SeismoAtlas is not an official warning service.