QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4ml

125 km E of McCarthy, Alaska

Yes. A magnitude 3.4 earthquake was recorded 125 km E of McCarthy, Alaska at 10:17 UTC on 2020-04-30, 10 km deep. 1 person has reported feeling it to USGS.

· 10 km deep · released about 1.9 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 3.4 (ml)
Depth
10 km below the surface
Felt
1 report · strongest reported intensity II
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2309 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 57 km (35 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 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 89,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,800× the energy of this one
  4. This earthquake M 3.4 about 1.9 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4× 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 4.0 on 2017-11-05 — about 7.9 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.1 109 km E of McCarthy, Alaska · 33 km SSW of this epicentre
  2. 5.7 152 km E of McCarthy, Alaska · 34 km SE of this epicentre
  3. 5.5 87 km ENE of McCarthy, Alaska · 41 km WNW of this epicentre
  4. 5.4 140 km SSE of Alcan Border, Alaska · 17 km ESE of this epicentre
  5. 5.4 136 km SSE of Alcan Border, Alaska · 26 km E 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 61.5205, -140.5772. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.5 126 km E of McCarthy, Alaska
  2. 2.5 122 km E of McCarthy, Alaska
  3. 1.6 129 km E of McCarthy, Alaska
  4. 2.7 127 km E of McCarthy, Alaska
  5. 1.6 132 km E of McCarthy, Alaska
  6. 1.6 128 km E of McCarthy, Alaska
  7. 4.9 126 km E of McCarthy, Alaska
  8. 2.3 146 km WNW of Haines Junction, Canada
  9. 2.2 114 km E of McCarthy, Alaska
  10. 1.9 103 km E of McCarthy, Alaska
  11. 1.5 101 km E of McCarthy, Alaska
  12. 1.5 97 km E of McCarthy, Alaska
  13. 1.8 129 km E of McCarthy, Alaska
  14. 1.7 131 km E of McCarthy, Alaska
  15. 1.9 99 km E 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.