QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

91 km SSW of False Pass, Alaska

Yes. A magnitude 3.0 earthquake was recorded 91 km SSW of False Pass, Alaska, at 8:09 pm AKDT on 25 July 2018 (04:09 UTC), 35 km deep.

· 35 km deep · released about 950 lb 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 3.0 (ml)
Depth
35 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1186 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 13 km (8 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 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 950 lb of TNT

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 4.8 on 2017-06-30 — about 500 times the energy of this one.

Before 2016, the USGS record lists 25 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 79 km SW of False Pass, Alaska · 15 km N of this epicentre
  2. 6.2 Unimak Island region, Alaska · 43 km SSE of this epicentre
  3. 6.2 102 km SSW of False Pass, Alaska · 20 km SSE of this epicentre
  4. 6.2 115 km ESE of Akutan, Alaska · 35 km S of this epicentre
  5. 6.0 106 km ESE of Akutan, Alaska · 25 km S 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 54.1516, -164.1591. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.0 89 km SW of False Pass, Alaska
  2. 3.8 111 km ESE of Akutan, Alaska
  3. 2.4 106 km SSW of False Pass, Alaska
  4. 2.3 104 km ESE of Akutan, Alaska
  5. 2.3 113 km SSW of False Pass, Alaska
  6. 2.8 69 km S of False Pass, Alaska
  7. 2.2 104 km S of False Pass, Alaska
  8. 2.4 106 km ESE of Akutan, Alaska
  9. 2.4 97 km SSW of False Pass, Alaska
  10. 2.2 108 km ESE of Akutan, Alaska
  11. 2.1 97 km E of Akutan, Alaska
  12. 2.2 87 km ESE of Akutan, Alaska
  13. 2.1 86 km ESE of Akutan, Alaska
  14. 3.3 80 km SSW of False Pass, Alaska
  15. 2.2 107 km ESE 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.