QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5ml

48 km E of Chase, Alaska

Yes. A magnitude 3.5 earthquake was recorded 48 km E of Chase, Alaska, at 2:05 pm AKDT on 18 May 2021 (22:05 UTC), 9.1 km deep. 6 people have reported feeling it to USGS.

· 9.1 km deep · released about 2.7 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Matanuska-Susitna Borough 33 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 3.5 (ml)
Depth
9.1 km below the surface
Felt
6 reports · strongest reported intensity V
Measured shaking
intensity III (ShakeMap)
Nearest
Matanuska-Susitna Borough, 33 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1937 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 63 km (39 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 2.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 63,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,800× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,000× the energy of this one
  4. This earthquake M 3.5 about 2.7 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 5.6× 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 4.6 on 2016-04-26 — about 45 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 5.8 37 km ENE of Susitna North, Alaska · 25 km S of this epicentre
  2. 5.4 54 km NE of Chase, Alaska · 41 km NNW of this epicentre
  3. 5.1 25 km ENE of Susitna North, Alaska · 32 km SSW of this epicentre
  4. 5.1 49 km NE of Chase, Alaska · 37 km NNW of this epicentre
  5. 5.0 70 km ENE of Chase, Alaska · 26 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 62.5183, -149.1804. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 33 km (20 mi) SSW earthquakes near Matanuska-Susitna Borough

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. 2.1 48 km E of Chase, Alaska
  2. 2.6 48 km N of Sutton-Alpine, Alaska
  3. 2.3 14 km E of Susitna North, Alaska
  4. 1.6 61 km S of Cantwell, Alaska
  5. 2.7 59 km SSW of Cantwell, Alaska
  6. 1.7 38 km ENE of Chase, Alaska
  7. 1.6 55 km ENE of Chase, Alaska
  8. 2.1 40 km NNW of Sutton-Alpine, Alaska
  9. 2.2 29 km NE of Chase, Alaska
  10. 2.4 52 km S of Cantwell, Alaska
  11. 1.8 50 km NNE of Chase, Alaska
  12. 2.3 46 km NE of Susitna North, Alaska
  13. 1.6 61 km N of Chickaloon, Alaska
  14. 1.7 Central Alaska
  15. 1.6 35 km ENE of Chase, 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.