QuakeIndex

ice quake · reviewed by a seismologist

M 2.3ml

Earthquake near Girdwood, AK

No earthquake was likely felt in Girdwood in the 24 hours to 7:32 am AKST (16:32 UTC). The last one was M 1.8, 8 km (5 mi) SE, at 10:01 am AKDT on 19 October 2026, estimated intensity II (weak) in town. Every earthquake near Girdwood

No: USGS classifies this as a ice quake, not an earthquake. A magnitude 2.3 ice quake was recorded 43 km (27 mi) east-northeast of Girdwood, AK, at 1:23 pm AKDT on 16 May 2021 (21:23 UTC), less than 1 km deep.

USGS: 34 km NNE of Whittier, Alaska

82 km (51 mi) ESE of Anchorage, AK

1:23 pm AKDT, May 16, 2021 · · 0.0 km deep · released about 85 lb of TNT

Every earthquake near Girdwood Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 49 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
1:23 pm AKDT on 16 May 2021 ()
Where
43 km (27 mi) east-northeast of Girdwood, AK · earthquakes near Girdwood
Magnitude
M 2.3 (ml)
Depth
0.0 km below the surface
Felt
no reports yet
Nearest
Anchorage Municipality, 49 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1978 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 20 km (12 mi) from the epicentre. In Girdwood, 43 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.

USGS catalogues this as ice quake, not an earthquake.

How big was it?

This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
  3. Around the size people start to feel M 3.0 11× the energy of this one
  4. This earthquake M 2.3 about 85 lb of TNT

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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 57 km ENE of Whittier, Alaska · 35 km E of this epicentre
  2. 6.4 22 km ENE of Whittier, Alaska · 23 km SSE of this epicentre
  3. 6.4 46 km WNW of Tatitlek, Alaska · 50 km E of this epicentre
  4. 6.3 27 km ENE of Whittier, Alaska · 21 km SSE of this epicentre
  5. 6.1 54 km WNW of Tatitlek, Alaska · 45 km E 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 61.0558, -148.4085. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 49 km (30 mi) WNW earthquakes near Anchorage Municipality
Chugach Census Area, AK 135 km (84 mi) ESE earthquakes near Chugach Census Area

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

Aftershocks so far

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

  1. 1.9 38 km ESE of Whittier, Alaska
  2. 1.8 42 km SE of Knik River, Alaska
  3. 2.1 13 km S of Knik River, Alaska
  4. 2.6 47 km SSW of Glacier View, Alaska
  5. 1.5 20 km ENE of Whittier, Alaska
  6. 1.5 39 km NNE of Whittier, Alaska
  7. 1.5 Southern Alaska
  8. 1.5 53 km NE of Whittier, Alaska
  9. 2.0 43 km NNE of Whittier, Alaska
  10. 1.8 24 km ESE of Whittier, Alaska
  11. 1.7 43 km NNE of Whittier, Alaska
  12. 1.5 17 km ESE of Whittier, Alaska
  13. 1.5 42 km NNE of Whittier, Alaska
  14. 1.8 7 km E of Whittier, Alaska
  15. 1.5 22 km ESE of Knik River, 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.