QuakeIndex

Earthquake · reviewed by a seismologist

M 5.0ml

Earthquake near Anchorage, AK

No earthquake was likely felt in Anchorage in the 24 hours to 1:10 pm AKST (22:10 UTC). The last one was M 3.5, 39 km (24 mi) SSW, at 4:48 pm AKDT on 27 October 2026, estimated intensity II (weak) in town; 98 felt reports to USGS. Every earthquake near Anchorage

This page: a magnitude 5.0 earthquake was recorded 9 km (6 mi) north-northwest of Anchorage, AK, at 6:03 pm AKST on 31 December 2018 (03:03 UTC), 44 km deep. 1,073 people have reported feeling it to USGS.

USGS: 7 km SSE of Point MacKenzie, Alaska

9 km (6 mi) NNW of Anchorage, AK

6:03 pm AKST, Dec 31, 2018 · · 44 km deep · released about 480 tons of TNT

Every earthquake near Anchorage Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 38 kmMatanuska-Susitna Borough 110 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
6:03 pm AKST on 31 December 2018 ()
Where
9 km (6 mi) north-northwest of Anchorage, AK · earthquakes near Anchorage
Magnitude
M 5.0 (ml)
Depth
44 km below the surface
Felt
1,073 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Anchorage Municipality, 38 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 325 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 188 km (117 mi) from the epicentre. In Anchorage, 9 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: Anchorage 9 km, intensity III · Eagle River 21 km, intensity III · Big Lake 25 km, intensity III · Knik-Fairview 30 km, intensity III · Tanaina 46 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 480 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16× the energy of this one
  3. Magna, Utah 2020 M 5.7 11× the energy of this one
  4. This earthquake M 5.0 about 480 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 1,000× 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 7.1 on 2018-11-30 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 22 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 20 km ENE of Beluga, Alaska · 44 km W of this epicentre
  2. 5.6 11 km NW of Big Lake, Alaska · 33 km NNW of this epicentre
  3. 5.6 5 km N of Susitna, Alaska · 45 km NW of this epicentre
  4. 5.5 2 km ENE of Eagle River, Alaska · 23 km E of this epicentre
  5. 5.5 9 km E of Susitna, Alaska · 34 km NW 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 61.2975, -149.9523. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 38 km (24 mi) ESE earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 110 km (68 mi) NNE earthquakes near Matanuska-Susitna Borough

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

Aftershocks so far

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

  1. 1.5 3 km NW of Point MacKenzie, Alaska
  2. 1.8 4 km NE of Point MacKenzie, Alaska
  3. 2.2 3 km SSE of Big Lake, Alaska
  4. 1.8 3 km SE of Big Lake, Alaska
  5. 3.6 6 km SSE of Point MacKenzie, Alaska
  6. 2.5 6 km S of Big Lake, Alaska
  7. 1.8 6 km WNW of Point MacKenzie, Alaska
  8. 1.6 8 km WSW of Knik, Alaska
  9. 1.7 8 km WNW of Point MacKenzie, Alaska
  10. 2.4 7 km W of Point MacKenzie, Alaska
  11. 3.0 3 km ESE of Big Lake, Alaska
  12. 2.5 4 km SSE of Big Lake, Alaska
  13. 3.2 13 km SW of Anchorage, Alaska
  14. 2.5 7 km SE of Point MacKenzie, Alaska
  15. 1.9 5 km NW of Point MacKenzie, 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.