QuakeIndex

Earthquake · reviewed by a seismologist

M 5.1mww

138 km SSE of False Pass, Alaska

Yes. A magnitude 5.1 earthquake was recorded 138 km SSE of False Pass, Alaska at 22:54 UTC on 2019-02-15, 35 km deep. 4 people have reported feeling it to USGS.

· 35 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
35 km below the surface
Felt
4 reports · strongest reported intensity II
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 203 km (126 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 since 2016 was M 5.9 on 2016-10-27 — about 16 times the energy of this one.

Before 2016, the USGS record lists 39 earthquakes of M5 or more within 50 km; the five largest:

  1. 8.6 The 1946 Unimak Island, Alaska Earthquake · 18 km SSE of this epicentre
  2. 6.2 172 km SSE of False Pass, Alaska · 35 km S of this epicentre
  3. 6.1 166 km S of False Pass, Alaska · 33 km SSW of this epicentre
  4. 6.0 155 km S of False Pass, Alaska · 41 km WSW of this epicentre
  5. 6.0 129 km S of False Pass, Alaska · 32 km W 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 53.6466, -162.9300. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.9 131 km SSE of False Pass, Alaska
  2. 4.1 111 km S of False Pass, Alaska
  3. 2.2 93 km SSE of False Pass, Alaska
  4. 2.9 107 km SSE of False Pass, Alaska
  5. 2.8 Unimak Island region, Alaska
  6. 2.2 108 km S of False Pass, Alaska
  7. 2.5 101 km S of False Pass, Alaska
  8. 2.0 107 km SSE of False Pass, Alaska
  9. 2.6 102 km S of False Pass, Alaska
  10. 2.2 96 km S of False Pass, Alaska
  11. 2.5 156 km S of False Pass, Alaska
  12. 2.4 118 km SSE of False Pass, Alaska
  13. 2.8 139 km S of False Pass, Alaska
  14. 2.3 111 km S of False Pass, Alaska
  15. 3.9 106 km S 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.