Earthquake · reviewed by a seismologist
M 4.1ml
Earthquake near Nikiski, AK
No earthquake was likely felt in Nikiski in the 24 hours to 3:51 am AKST (12:51 UTC). The last one was M 4.3, 58 km (36 mi) SSE, at 2:30 am AKST on 1 November 2026, estimated intensity II (weak) in town; 115 felt reports to USGS. Every earthquake near Nikiski
This page: a magnitude 4.1 earthquake was recorded 4 km (2 mi) east-southeast of Nikiski, AK, at 1:05 pm AKDT on 4 September 2017 (21:05 UTC), 68 km deep. 138 people have reported feeling it to USGS.
USGS: 4 km ESE of Nikiski, Alaska
93 km (58 mi) SW of Anchorage, AK
- When
- 1:05 pm AKDT on 4 September 2017 ()
- Where
- 4 km (2 mi) east-southeast of Nikiski, AK · earthquakes near Nikiski
- Magnitude
- M 4.1 (ml)
- Depth
- 68 km below the surface
- Felt
- 138 reports · strongest reported intensity III
- Measured shaking
- intensity III (ShakeMap)
- USGS impact alert
- green
- Tsunami
- USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
- Nearest
- Kenai Peninsula Borough, 70 km WSW
- Nearest mapped fault
- Middle Ground Shoal anticline (Cook Inlet folds), 17 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1192 days ago
Earthquake alerts for Nikiski, AK
Get a notification in this browser when USGS records an earthquake near Nikiski, AK. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
At this magnitude and depth, people at rest would likely notice it out to about 80 km (50 mi) from the epicentre. In Nikiski, 4 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Nikiski 4 km, intensity II · Kenai 14 km, intensity II · Soldotna 23 km, intensity II · Kalifornsky 29 km, intensity II · Sterling 29 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 7,900× the energy of this one
- Mineral, Virginia 2011 M 5.8 350× the energy of this one
- Magna, Utah 2020 M 5.7 250× the energy of this one
- This earthquake M 4.1 about 21 tons of TNT
- Around the size people start to feel M 3.0 this one released 45× more
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
The largest earthquake within 50 km since 2016 was M 4.3 on 2017-07-07 — about 2 times the energy of this one.
Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:
- 6.8 Southern Alaska · 47 km N of this epicentre
- 6.8 24 km ENE of Sterling, Alaska · 45 km E of this epicentre
- 6.7 6 km WNW of Nikiski, Alaska · 10 km WNW of this epicentre
- 6.4 19 km SSE of Tyonek, Alaska · 26 km NNE of this epicentre
- 5.7 19 km NNW of Nikiski, Alaska · 22 km NNW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 60.6788, -151.2195. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Kenai Peninsula Borough, AK | 70 km (43 mi) | WSW | earthquakes near Kenai Peninsula Borough |
| Anchorage Municipality, AK | 118 km (73 mi) | ENE | earthquakes near Anchorage Municipality |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
54 earthquakes have been recorded within 50 km since this one.
- 1.5 17 km N of Nikiski, Alaska
- 1.5 4 km NNE of Kenai, Alaska
- 1.9 11 km WSW of Tyonek, Alaska
- 1.5 6 km SW of Point Possession, Alaska
- 1.6 23 km WNW of Nikiski, Alaska
- 1.6 19 km N of Nikiski, Alaska
- 1.8 25 km SW of Tyonek, Alaska
- 1.6 17 km ESE of Kasilof, Alaska
- 1.5 21 km N of Nikiski, Alaska
- 1.5 3 km WNW of Point Possession, Alaska
- 1.6 13 km SE of Tyonek, Alaska
- 1.8 Southern Alaska
- 1.6 21 km SSW of Tyonek, Alaska
- 2.4 11 km SW of Tyonek, Alaska
- 2.2 17 km ENE of Nikiski, Alaska
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.