QuakeIndex

Earthquake · reviewed by a seismologist

M 5.2mww

56 km E of Atka, Alaska

Yes. A magnitude 5.2 earthquake was recorded 56 km E of Atka, Alaska at 10:39 UTC on 2017-03-01, 52 km deep.

· 52 km deep · released about 950 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 5.2 (mww)
Depth
52 km below the surface
Felt
no reports yet
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1197 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 212 km (132 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 950 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 180× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 7.9× the energy of this one
  3. Magna, Utah 2020 M 5.7 5.6× the energy of this one
  4. This earthquake M 5.2 about 950 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2,000× 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.9 on 2016-03-19.

Before 2016, the USGS record lists 24 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 75 km SE of Atka, Alaska · 39 km S of this epicentre
  2. 6.0 65 km SE of Atka, Alaska · 47 km SSW of this epicentre
  3. 5.9 52 km SE of Atka, Alaska · 47 km SSW of this epicentre
  4. 5.9 55 km ESE of Atka, Alaska · 19 km SSW of this epicentre
  5. 5.8 66 km E of Atka, Alaska · 15 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 52.1708, -173.3725. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.1 50 km ENE of Atka, Alaska
  2. 3.4 70 km ENE of Atka, Alaska
  3. 2.0 77 km SE of Atka, Alaska
  4. 1.9 45 km SE of Atka, Alaska
  5. 2.8 40 km ESE of Atka, Alaska
  6. 3.9 29 km ESE of Atka, Alaska
  7. 2.0 45 km E of Atka, Alaska
  8. 2.9 45 km E of Atka, Alaska
  9. 2.3 40 km NE of Atka, Alaska
  10. 2.1 33 km SE of Atka, Alaska
  11. 2.1 28 km ESE of Atka, Alaska
  12. 2.2 43 km SE of Atka, Alaska
  13. 2.2 57 km ESE of Atka, Alaska
  14. 2.0 68 km ESE of Atka, Alaska
  15. 1.8 37 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.