QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7ml

156 km S of McCarthy, Alaska

Yes. A magnitude 3.7 earthquake was recorded 156 km S of McCarthy, Alaska at 06:00 UTC on 2024-08-18, 15 km deep.

· 15 km deep · released about 5.4 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N
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 3.7 (ml)
Depth
15 km below the surface
Felt
no reports yet
Measured shaking
intensity III (ShakeMap)
Nearest mapped fault
Pamplona fault, 10 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 748 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 74 km (46 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 5.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 32,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,000× the energy of this one
  4. This earthquake M 3.7 about 5.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 11× 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 6.7 163 km W of Yakutat, Alaska · 40 km SE of this epicentre
  2. 6.1 171 km SE of Cordova, Alaska · 49 km SSW of this epicentre
  3. 5.8 162 km WNW of Yakutat, Alaska · 34 km ESE of this epicentre
  4. 5.5 164 km S of McCarthy, Alaska · 31 km ESE 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 60.0296, -143.1002. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.9 117 km S of McCarthy, Alaska
  2. 2.6 122 km S of McCarthy, Alaska
  3. 1.7 116 km S of McCarthy, Alaska
  4. 2.2 126 km SSW of McCarthy, Alaska
  5. 1.8 124 km SSW of McCarthy, Alaska
  6. 1.8 110 km S of McCarthy, Alaska
  7. 1.8 155 km S of McCarthy, Alaska
  8. 2.6 117 km S of McCarthy, Alaska
  9. 1.8 109 km S of McCarthy, Alaska
  10. 1.6 110 km S of McCarthy, Alaska
  11. 2.5 181 km SE of Cordova, Alaska
  12. 3.1 116 km SSW of McCarthy, Alaska
  13. 2.0 109 km S of McCarthy, Alaska
  14. 1.6 112 km S of McCarthy, Alaska
  15. 1.6 120 km S of McCarthy, 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.