QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

55 km ESE of Whittier, Alaska

Yes. A magnitude 1.8 earthquake was recorded 55 km ESE of Whittier, Alaska, at 2:29 pm AKST on 19 November 2021 (23:29 UTC), 4.2 km deep.

· 4.2 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Chugach Census Area 84 kmAnchorage Municipality 103 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
Magnitude
M 1.8 (ml)
Depth
4.2 km below the surface
Felt
no reports yet
Nearest
Chugach Census Area, 84 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1795 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 13 km (8 mi) from the epicentre. 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.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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

The largest earthquake within 50 km since 2016 was M 5.3 on 2017-11-27 — about 180,000 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

  1. 9.2 The 1964 Prince William Sound, Alaska Earthquake · 34 km NE of this epicentre
  2. 7.0 52 km NE of Chenega, Alaska · 38 km SE of this epicentre
  3. 6.7 Prince William Sound, Alaska · 35 km E of this epicentre
  4. 6.6 57 km ENE of Whittier, Alaska · 42 km N of this epicentre
  5. 6.6 37 km WNW of Tatitlek, Alaska · 48 km NNE 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 60.6530, -147.7003. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Chugach Census Area, AK 84 km (52 mi) ESE earthquakes near Chugach Census Area
Anchorage Municipality, AK 103 km (64 mi) NW earthquakes near Anchorage Municipality

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 57 km ESE of Whittier, Alaska
  2. 1.7 53 km NE of Chenega, Alaska
  3. 1.7 52 km W of Tatitlek, Alaska
  4. 1.5 Southern Alaska
  5. 2.1 44 km WSW of Tatitlek, Alaska
  6. 1.5 33 km WSW of Tatitlek, Alaska
  7. 1.7 58 km NNE of Chenega, Alaska
  8. 1.5 35 km WNW of Tatitlek, Alaska
  9. 1.5 56 km NE of Chenega, Alaska
  10. 2.0 51 km WSW of Tatitlek, Alaska
  11. 1.8 52 km SW of Tatitlek, Alaska
  12. 1.5 55 km WSW of Tatitlek, Alaska
  13. 3.8 34 km WNW of Tatitlek, Alaska
  14. 1.6 52 km SW of Tatitlek, Alaska
  15. 1.5 32 km NNE of Chenega, 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.