QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mwr

Earthquake near Nikiski, AK

No earthquake was likely felt in Nikiski in the 24 hours to 8:06 am AKST (17:06 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 4.8 earthquake was recorded 41 km (26 mi) northeast of Nikiski, AK, at 4:16 pm AKDT on 9 April 2023 (00:16 UTC), 56 km deep. 975 people have reported feeling it to USGS.

USGS: Kenai Peninsula, Alaska

56 km (35 mi) WSW of Anchorage, AK

4:16 pm AKDT, Apr 9, 2023 · · 56 km deep · released about 240 tons of TNT

Every earthquake near Nikiski Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 86 kmKenai Peninsula Borough 107 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
4:16 pm AKDT on 9 April 2023 ()
Where
41 km (26 mi) northeast of Nikiski, AK · earthquakes near Nikiski
Magnitude
M 4.8 (mwr)
Depth
56 km below the surface
Felt
975 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Anchorage Municipality, 86 km ENE
Nearest mapped fault
Granite Point anticline (Cook Inlet folds), 24 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 1079 days ago

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 161 km (100 mi) from the epicentre. In Nikiski, 41 km away, the estimate is intensity III (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 41 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 710× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 240 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 500× 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

Tied for the largest within 50 km (31 mi) since 2016, with M 4.8 on 2022-07-12.

Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 Southern Alaska · 19 km NW of this epicentre
  2. 6.8 4 km NE of Beluga, Alaska · 23 km NNW of this epicentre
  3. 6.8 24 km ENE of Sterling, Alaska · 44 km SSE of this epicentre
  4. 6.7 6 km WNW of Nikiski, Alaska · 43 km SW of this epicentre
  5. 6.4 19 km SSE of Tyonek, Alaska · 16 km SW 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 60.9876, -150.8293. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 86 km (53 mi) ENE earthquakes near Anchorage Municipality
Kenai Peninsula Borough, AK 107 km (66 mi) SW earthquakes near Kenai Peninsula Borough

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

59 earthquakes have been recorded within 50 km since this one.

  1. 1.7 Southern Alaska
  2. 1.6 17 km SSW of Tyonek, Alaska
  3. 1.5 28 km N of Beluga, Alaska
  4. 1.6 17 km SSW of Point Possession, Alaska
  5. 2.7 1 km NE of Beluga, Alaska
  6. 2.4 4 km SSE of Tyonek, Alaska
  7. 1.5 7 km WNW of Tyonek, Alaska
  8. 1.6 9 km NNE of Nikiski, Alaska
  9. 4.6 Southern Alaska
  10. 1.7 14 km SSE of Tyonek, Alaska
  11. 1.8 16 km SW of Susitna, Alaska
  12. 1.6 16 km N of Nikiski, Alaska
  13. 1.7 1 km NE of Beluga, Alaska
  14. 1.7 13 km ESE of Beluga, Alaska
  15. 1.8 20 km E of Beluga, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.