QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9md

Virgin Islands

Yes. A magnitude 3.9 earthquake was recorded in the Virgin Islands at 14:00 UTC on 2023-07-22, 37 km deep.

· 37 km deep · released about 9.3 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 3.9 (md)
Depth
37 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1140 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 78 km (48 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 9.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 18,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 810× the energy of this one
  3. Magna, Utah 2020 M 5.7 580× the energy of this one
  4. This earthquake M 3.9 about 9.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 19× 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 in our catalogue was M 5.0 on 2019-10-06 — about 45 times the energy of this one.

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 19.6320, -64.3275. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.0 172 km N of Cruz Bay, U.S. Virgin Islands
  2. 3.9 152 km N of Cruz Bay, U.S. Virgin Islands
  3. 3.3 102 km NNE of Cruz Bay, U.S. Virgin Islands
  4. 4.0 152 km N of Cruz Bay, U.S. Virgin Islands
  5. 4.0 154 km NNE of Cruz Bay, U.S. Virgin Islands
  6. 3.7 154 km NNE of Cruz Bay, U.S. Virgin Islands
  7. 3.8 134 km NNE of Cruz Bay, U.S. Virgin Islands
  8. 3.6 165 km NNE of Cruz Bay, U.S. Virgin Islands
  9. 3.9 163 km NNE of Cruz Bay, U.S. Virgin Islands
  10. 3.7 168 km NNE of Cruz Bay, U.S. Virgin Islands
  11. 3.6 153 km NNE of Cruz Bay, U.S. Virgin Islands
  12. 3.9 149 km N of Cruz Bay, U.S. Virgin Islands
  13. 4.0 144 km N of Cruz Bay, U.S. Virgin Islands
  14. 3.8 150 km N of Cruz Bay, U.S. Virgin Islands
  15. 3.9 141 km N of Cruz Bay, U.S. Virgin Islands

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.