QuakeIndex

Earthquake · reviewed by a seismologist

M 4.2mb

37 km WNW of False Pass, Alaska

Yes. A magnitude 4.2 earthquake was recorded 37 km WNW of False Pass, Alaska, at 7:03 am AKDT on 17 May 2024 (15:03 UTC), 146 km deep. 1 person has reported feeling it to USGS.

· 146 km deep · released about 30 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 4.2 (mb)
Depth
146 km below the surface
Felt
1 report · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 840 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 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 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 5,600× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 250× the energy of this one
  3. Magna, Utah 2020 M 5.7 180× the energy of this one
  4. This earthquake M 4.2 about 30 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 63× 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 (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 5.9 27 km W of False Pass, Alaska · 17 km SSE of this epicentre
  2. 5.9 14 km NNE of False Pass, Alaska · 39 km E of this epicentre
  3. 5.5 66 km NNW of False Pass, Alaska · 44 km N of this epicentre
  4. 5.1 52 km W of False Pass, Alaska · 27 km SW of this epicentre
  5. 5.0 29 km W of False Pass, Alaska · 19 km SSE 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 55.0174, -163.9303. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.8 21 km SSW of False Pass, Alaska
  2. 2.0 51 km W of False Pass, Alaska
  3. 2.9 21 km WSW of False Pass, Alaska
  4. 2.7 28 km WNW of False Pass, Alaska
  5. 1.9 33 km SW of False Pass, Alaska
  6. 2.0 28 km SW of False Pass, Alaska
  7. 2.9 48 km WSW of False Pass, Alaska
  8. 3.0 26 km NNW of False Pass, Alaska
  9. 1.6 30 km WSW of False Pass, Alaska
  10. 2.1 68 km WSW of False Pass, Alaska
  11. 2.3 16 km S of False Pass, Alaska
  12. 2.9 10 km SSW of False Pass, Alaska
  13. 4.3 15 km WNW of False Pass, Alaska
  14. 1.5 42 km SW of False Pass, Alaska
  15. 2.2 4 km N 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.