QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

87 km S of False Pass, Alaska

Yes. A magnitude 2.1 earthquake was recorded 87 km S of False Pass, Alaska, at 3:33 pm AKST on 17 February 2017 (00:33 UTC), 45 km deep.

· 45 km deep · released about 43 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 2.1 (ml)
Depth
45 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1197 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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 5.1 on 2016-10-27 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 Unimak Island region, Alaska · 47 km SW of this epicentre
  2. 6.2 102 km SSW of False Pass, Alaska · 38 km WSW of this epicentre
  3. 6.2 115 km ESE of Akutan, Alaska · 50 km WSW of this epicentre
  4. 6.0 129 km S of False Pass, Alaska · 42 km S of this epicentre
  5. 6.0 96 km SSW of False Pass, Alaska · 22 km WSW 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 54.0690, -163.4335. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.0 101 km SSE of False Pass, Alaska
  2. 2.4 107 km S of False Pass, Alaska
  3. 3.1 89 km S of False Pass, Alaska
  4. 2.1 108 km SSW of False Pass, Alaska
  5. 2.4 108 km S of False Pass, Alaska
  6. 2.0 100 km S of False Pass, Alaska
  7. 2.4 118 km SSW of False Pass, Alaska
  8. 1.6 120 km SSW of False Pass, Alaska
  9. 1.6 Unimak Island region, Alaska
  10. 2.0 114 km SSW of False Pass, Alaska
  11. 2.2 94 km S of False Pass, Alaska
  12. 2.2 92 km SSW of False Pass, Alaska
  13. 2.2 126 km S of False Pass, Alaska
  14. 2.0 40 km SSW of False Pass, Alaska
  15. 3.0 87 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.