QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5mb

191 km SSE of Sand Point, Alaska

Yes. A magnitude 3.5 earthquake was recorded 191 km SSE of Sand Point, Alaska at 00:59 UTC on 2022-04-28, 10 km deep.

· 10 km deep · released about 2.7 tons of TNT

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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 3.5 (mb)
Depth
10 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 2 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1593 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 5.4 on 2021-06-18 — about 710 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.7 208 km SSE of Sand Point, Alaska · 18 km SSE of this epicentre
  2. 5.5 233 km S of Sand Point, Alaska · 45 km S of this epicentre
  3. 5.0 188 km SSE of Sand Point, Alaska · 3 km N 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 53.6596, -159.8740. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.8 146 km SSE of Sand Point, Alaska
  2. 2.6 209 km SSE of Sand Point, Alaska
  3. 3.0 198 km S of Sand Point, Alaska
  4. 2.0 217 km S of Sand Point, Alaska
  5. 2.8 215 km S of Sand Point, Alaska
  6. 1.9 146 km SSE of Sand Point, Alaska
  7. 2.1 156 km SSE of Sand Point, Alaska
  8. 2.4 220 km S of Sand Point, Alaska
  9. 2.0 147 km SSE of Sand Point, Alaska
  10. 1.8 144 km SSE of Sand Point, Alaska
  11. 1.8 145 km SSE of Sand Point, Alaska
  12. 1.9 145 km SSE of Sand Point, Alaska
  13. 2.1 146 km SSE of Sand Point, Alaska
  14. 2.0 146 km SSE of Sand Point, Alaska
  15. 3.1 148 km SSE of Sand Point, 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.