QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mwr

189 km E of Atka, Alaska

Yes. A magnitude 4.9 earthquake was recorded 189 km E of Atka, Alaska at 23:41 UTC on 2024-04-10, 37 km deep. 2 people have reported feeling it to USGS.

· 37 km deep · released about 340 tons of TNT

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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 4.9 (mwr)
Depth
37 km below the surface
Felt
2 reports · strongest reported intensity II
Measured shaking
intensity II (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 880 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 178 km (111 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 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 500× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 22× the energy of this one
  3. Magna, Utah 2020 M 5.7 16× the energy of this one
  4. This earthquake M 4.9 about 340 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 710× 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 5.9 on 2018-08-25 — about 32 times the energy of this one.

Before 2016, the USGS record lists 54 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.3 Fox Islands, Aleutian Islands, Alaska · 31 km WSW of this epicentre
  2. 6.9 170 km E of Atka, Alaska · 19 km W of this epicentre
  3. 6.2 173 km WSW of Nikolski, Alaska · 46 km N of this epicentre
  4. 6.1 185 km ESE of Atka, Alaska · 37 km SSW of this epicentre
  5. 6.1 188 km E of Atka, Alaska · 8 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 52.1824, -171.4322. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.0 195 km E of Atka, Alaska
  2. 3.3 190 km E of Atka, Alaska
  3. 3.0 188 km E of Atka, Alaska
  4. 5.6 165 km SW of Nikolski, Alaska
  5. 2.5 163 km WSW of Nikolski, Alaska
  6. 3.2 182 km ESE of Atka, Alaska
  7. 3.3 172 km E of Atka, Alaska
  8. 4.2 171 km E of Atka, Alaska
  9. 2.9 173 km ESE of Atka, Alaska
  10. 2.8 171 km WSW of Nikolski, Alaska
  11. 3.1 173 km E of Atka, Alaska
  12. 3.5 192 km ESE of Atka, Alaska
  13. 2.3 169 km WSW of Nikolski, Alaska
  14. 3.6 176 km WSW of Nikolski, Alaska
  15. 2.9 191 km ESE of Atka, 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.