QuakeIndex

Earthquake · reviewed by a seismologist

M 4.6mwr

Alaska Peninsula

Yes. A magnitude 4.6 earthquake was recorded in the Alaska Peninsula at 11:32 UTC on 2023-07-28, 6.0 km deep. 1 person has reported feeling it to USGS.

· 6.0 km deep · released about 120 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 4.6 (mwr)
Depth
6.0 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity III (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1140 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 149 km (93 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 120 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,400× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 63× the energy of this one
  3. Magna, Utah 2020 M 5.7 45× the energy of this one
  4. This earthquake M 4.6 about 120 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 250× 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 in our catalogue was M 4.8 on 2022-08-17 — about 2 times the energy of this one.

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 56.2871, -155.6472. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 87 km WSW of Akhiok, Alaska
  2. 1.8 105 km SW of Akhiok, Alaska
  3. 1.9 121 km WSW of Akhiok, Alaska
  4. 2.4 114 km WSW of Akhiok, Alaska
  5. 2.3 124 km WSW of Akhiok, Alaska
  6. 2.6 85 km WSW of Akhiok, Alaska
  7. 2.4 101 km SW of Akhiok, Alaska
  8. 1.9 122 km WSW of Akhiok, Alaska
  9. 2.2 112 km WSW of Akhiok, Alaska
  10. 1.7 79 km WSW of Akhiok, Alaska
  11. 2.1 126 km WSW of Akhiok, Alaska
  12. 2.2 130 km WSW of Akhiok, Alaska
  13. 1.6 87 km SW of Akhiok, Alaska
  14. 2.2 132 km SSW of Akhiok, Alaska
  15. 1.9 87 km WSW of Akhiok, 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.