QuakeIndex

Earthquake · reviewed by a seismologist

M 5.1mww

126 km SE of Akutan, Alaska

Yes. A magnitude 5.1 earthquake was recorded 126 km SE of Akutan, Alaska, at 10:35 pm AKDT on 23 May 2017 (06:35 UTC), 10 km deep. 1 person has reported feeling it to USGS.

· 10 km deep · released about 670 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 5.1 (mww)
Depth
10 km below the surface
Felt
1 report · strongest reported intensity I
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 326 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 206 km (128 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 670 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11× the energy of this one
  3. Magna, Utah 2020 M 5.7 7.9× the energy of this one
  4. This earthquake M 5.1 about 670 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 1,400× 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 4.7 on 2016-09-15.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 92 km SE of Akutan, Alaska · 40 km NNW of this epicentre
  2. 6.5 83 km SE of Akutan, Alaska · 48 km NNW of this epicentre
  3. 6.2 136 km SE of Akutan, Alaska · 30 km ENE of this epicentre
  4. 6.2 156 km SE of Akutan, Alaska · 32 km ESE of this epicentre
  5. 6.1 136 km ESE of Akutan, Alaska · 40 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 53.3072, -164.4538. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 107 km SE of Akutan, Alaska
  2. 2.6 141 km ESE of Akutan, Alaska
  3. 1.9 85 km SE of Akutan, Alaska
  4. 2.3 136 km SSE of Akutan, Alaska
  5. 2.5 175 km SE of Akutan, Alaska
  6. 2.3 89 km SE of Akutan, Alaska
  7. 3.2 103 km ESE of Akutan, Alaska
  8. 2.9 99 km ESE of Akutan, Alaska
  9. 3.1 105 km ESE of Akutan, Alaska
  10. 2.3 95 km SE of Akutan, Alaska
  11. 2.2 109 km SE of Akutan, Alaska
  12. 2.0 91 km SE of Akutan, Alaska
  13. 2.4 130 km ESE of Akutan, Alaska
  14. 2.2 119 km SE of Akutan, Alaska
  15. 2.3 130 km SSE of Akutan, 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.