QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8ml

Earthquake near Girdwood, AK

No earthquake was likely felt in Girdwood in the 24 hours to 5:42 am AKST (14:42 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

This page: a magnitude 3.8 earthquake was recorded 48 km (30 mi) east of Girdwood, AK, at 1:37 pm AKDT on 31 July 2024 (21:37 UTC), 31 km deep. 3 people have reported feeling it to USGS.

USGS: 33 km NE of Whittier, Alaska

89 km (56 mi) ESE of Anchorage, AK

1:37 pm AKDT, Jul 31, 2024 · · 31 km deep · released about 7.6 tons of TNT

Every earthquake near Girdwood Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 56 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
1:37 pm AKDT on 31 July 2024 ()
Where
48 km (30 mi) east of Girdwood, AK · earthquakes near Girdwood
Magnitude
M 3.8 (ml)
Depth
31 km below the surface
Felt
3 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Anchorage Municipality, 56 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 763 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 76 km (47 mi) from the epicentre. In Girdwood, 48 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: Girdwood 48 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 22,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 710× the energy of this one
  4. This earthquake M 3.8 about 7.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 16× 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

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

Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 57 km ENE of Whittier, Alaska · 29 km E of this epicentre
  2. 6.4 22 km ENE of Whittier, Alaska · 17 km S of this epicentre
  3. 6.4 46 km WNW of Tatitlek, Alaska · 43 km E of this epicentre
  4. 6.3 27 km ENE of Whittier, Alaska · 13 km SSE of this epicentre
  5. 6.1 54 km WNW of Tatitlek, Alaska · 39 km ENE 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 61.0057, -148.2946. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 56 km (35 mi) WNW earthquakes near Anchorage Municipality
Chugach Census Area, AK 127 km (79 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. 1.8 25 km SSE of Whittier, Alaska
  2. 1.6 54 km S of Glacier View, Alaska
  3. 1.6 34 km NNE of Whittier, Alaska
  4. 2.0 23 km ENE of Whittier, Alaska
  5. 1.6 51 km ENE of Whittier, Alaska
  6. 2.2 25 km N of Whittier, Alaska
  7. 2.0 57 km S of Glacier View, Alaska
  8. 1.5 23 km ESE of Whittier, Alaska
  9. 1.5 50 km S of Glacier View, Alaska
  10. 1.6 64 km NE of Whittier, Alaska
  11. 1.5 44 km ENE of Whittier, Alaska
  12. 1.6 55 km ENE of Whittier, Alaska
  13. 1.5 18 km NNE of Whittier, Alaska
  14. 1.5 28 km SSE of Knik River, Alaska
  15. 1.9 25 km SSE of Whittier, 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.