QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mb

98 km SSE of False Pass, Alaska

Yes. A magnitude 4.5 earthquake was recorded 98 km SSE of False Pass, Alaska, at 1:47 am AKDT on 3 July 2019 (09:47 UTC), 35 km deep.

· 35 km deep · released about 85 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 4.5 (mb)
Depth
35 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1897 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 135 km (84 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 85 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 89× the energy of this one
  3. Magna, Utah 2020 M 5.7 63× the energy of this one
  4. This earthquake M 4.5 about 85 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 180× 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

Tied for the largest within 50 km (31 mi) since 2016, with M 4.5 on 2016-03-23.

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

  1. 6.5 88 km SE of False Pass, Alaska · 11 km NNW of this epicentre
  2. 5.8 112 km SE of False Pass, Alaska · 14 km SE of this epicentre
  3. 5.8 60 km SSW of King Cove, Alaska · 47 km N of this epicentre
  4. 5.7 88 km SE of False Pass, Alaska · 12 km N of this epicentre
  5. 5.7 99 km SE of False Pass, Alaska · 1 km ENE 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 54.1153, -162.5674. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.0 102 km SE of False Pass, Alaska
  2. 3.8 80 km SE of False Pass, Alaska
  3. 2.8 95 km SSE of False Pass, Alaska
  4. 1.8 95 km S of King Cove, Alaska
  5. 2.5 69 km SSE of False Pass, Alaska
  6. 1.8 82 km S of King Cove, Alaska
  7. 1.6 63 km SSW of King Cove, Alaska
  8. 1.7 84 km SE of False Pass, Alaska
  9. 2.2 Alaska Peninsula
  10. 1.9 61 km SSE of False Pass, Alaska
  11. 2.8 56 km SE of False Pass, Alaska
  12. 2.1 75 km SE of False Pass, Alaska
  13. 2.9 102 km SE of False Pass, Alaska
  14. 2.7 96 km SE of False Pass, Alaska
  15. 1.8 78 km SE of False Pass, 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.