QuakeIndex

Earthquake · reviewed by a seismologist

M 4.3ml

85 km S of McCarthy, Alaska

Yes. A magnitude 4.3 earthquake was recorded 85 km S of McCarthy, Alaska at 23:10 UTC on 2020-08-09, 9.4 km deep. 1 person has reported feeling it to USGS.

· 9.4 km deep · released about 43 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 4.3 (ml)
Depth
9.4 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1558 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, people at rest would likely notice it out to about 121 km (75 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 43 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 4,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 180× the energy of this one
  3. Magna, Utah 2020 M 5.7 130× the energy of this one
  4. This earthquake M 4.3 about 43 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 89× 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

Tied for the largest within 50 km (31 mi) since 2016, with M 4.3 on 2017-11-13.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.7 84 km SSW of McCarthy, Alaska · 36 km WNW of this epicentre
  2. 5.2 84 km SSW of McCarthy, Alaska · 40 km WNW of this epicentre
  3. 5.2 90 km SSW of McCarthy, Alaska · 38 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 60.6691, -143.0261. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.6 70 km SSW of McCarthy, Alaska
  2. 1.5 124 km S of McCarthy, Alaska
  3. 1.6 104 km S of McCarthy, Alaska
  4. 1.6 122 km S of McCarthy, Alaska
  5. 1.7 102 km S of McCarthy, Alaska
  6. 2.2 97 km S of McCarthy, Alaska
  7. 1.9 97 km S of McCarthy, Alaska
  8. 1.8 103 km S of McCarthy, Alaska
  9. 1.7 130 km S of McCarthy, Alaska
  10. 2.1 105 km S of McCarthy, Alaska
  11. 1.6 94 km S of McCarthy, Alaska
  12. 1.5 97 km S of McCarthy, Alaska
  13. 1.5 128 km S of McCarthy, Alaska
  14. 1.7 102 km S of McCarthy, Alaska
  15. 1.6 95 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.