QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

98 km E of Chignik, Alaska

Yes. A magnitude 1.9 earthquake was recorded 98 km E of Chignik, Alaska at 05:32 UTC on 2022-02-20, 1.5 km deep.

· 1.5 km deep · released about 21 lb of TNT

10 km30 km60 km120 km N
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 1.9 (ml)
Depth
1.5 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1696 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 15 km (9 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 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 500,000× the energy of this one
  3. Around the size people start to feel M 3.0 45× the energy of this one
  4. This earthquake M 1.9 about 21 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 6.9 on 2021-10-11 — about 32,000,000 times the energy of this one.

Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 117 km SSE of Ugashik, Alaska · 29 km ENE of this epicentre
  2. 6.5 60 km ENE of Chignik, Alaska · 40 km W of this epicentre
  3. 6.4 61 km ENE of Chignik, Alaska · 44 km WNW of this epicentre
  4. 6.4 77 km ESE of Chignik, Alaska · 43 km SSW of this epicentre
  5. 6.4 104 km SSE of Ugashik, Alaska · 21 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 56.4711, -156.8476. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.3 116 km E of Chignik, Alaska
  2. 1.7 102 km E of Chignik, Alaska
  3. 1.8 120 km SSE of Ugashik, Alaska
  4. 2.2 112 km SSE of Ugashik, Alaska
  5. 1.6 116 km ESE of Chignik, Alaska
  6. 2.4 95 km ENE of Chignik, Alaska
  7. 1.7 115 km E of Chignik, Alaska
  8. 1.6 108 km SSE of Ugashik, Alaska
  9. 2.2 119 km E of Chignik, Alaska
  10. 1.6 75 km E of Chignik, Alaska
  11. 2.5 110 km E of Chignik, Alaska
  12. 3.1 118 km E of Chignik, Alaska
  13. 2.3 119 km E of Chignik, Alaska
  14. 2.7 123 km E of Chignik, Alaska
  15. 2.2 87 km S of Ugashik, 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.