QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

39 km ESE of Whittier, Alaska

Yes. A magnitude 1.7 earthquake was recorded 39 km ESE of Whittier, Alaska, at 12:23 am AKDT on 3 September 2020 (08:23 UTC), 9.9 km deep.

· 9.9 km deep · released about 11 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 89 kmChugach Census Area 101 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 1.7 (ml)
Depth
9.9 km below the surface
Felt
no reports yet
Nearest
Anchorage Municipality, 89 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2250 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 7 km (4 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 11 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 89× the energy of this one
  4. This earthquake M 1.7 about 11 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 4.0 on 2018-04-11 — about 2,800 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 9.2 The 1964 Prince William Sound, Alaska Earthquake · 46 km NE of this epicentre
  2. 6.6 57 km ENE of Whittier, Alaska · 43 km NNE of this epicentre
  3. 6.4 Prince William Sound, Alaska · 47 km ESE of this epicentre
  4. 6.4 22 km ENE of Whittier, Alaska · 27 km NW of this epicentre
  5. 6.4 46 km WNW of Tatitlek, Alaska · 45 km NE 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 60.6613, -148.0090. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 89 km (56 mi) NW earthquakes near Anchorage Municipality
Chugach Census Area, AK 101 km (62 mi) E earthquakes near Chugach Census Area

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

Aftershocks so far

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

  1. 2.3 58 km ESE of Whittier, Alaska
  2. 1.7 55 km NNE of Chenega, Alaska
  3. 1.7 56 km ENE of Whittier, Alaska
  4. 1.7 60 km WSW of Tatitlek, Alaska
  5. 1.7 59 km WSW of Tatitlek, Alaska
  6. 1.9 51 km W of Tatitlek, Alaska
  7. 1.6 33 km NNE of Whittier, Alaska
  8. 1.5 45 km W of Tatitlek, Alaska
  9. 1.5 52 km WSW of Tatitlek, Alaska
  10. 2.0 36 km NNE of Chenega, Alaska
  11. 1.8 50 km ESE of Whittier, Alaska
  12. 1.8 39 km NNE of Chenega, Alaska
  13. 2.1 38 km NNW of Chenega, Alaska
  14. 1.7 45 km NE of Chenega, Alaska
  15. 1.9 51 km E of Tatitlek, AK

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.