QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9md

157 km N of Cruz Bay, U.S. Virgin Islands

Yes. A magnitude 3.9 earthquake was recorded 157 km N of Cruz Bay, U.S. Virgin Islands at 11:03 UTC on 2022-07-06, 54 km deep.

· 54 km deep · released about 11 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
54 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1521 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 71 km (44 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 11 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 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 5.0 on 2019-10-06 — about 39 times the energy of this one.

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

  1. 6.2 131 km NNE of Cruz Bay, U.S. Virgin Islands · 29 km SSE of this epicentre
  2. 5.0 122 km N of Charlotte Amalie, U.S. Virgin Islands · 48 km SW of this epicentre
  3. 5.0 116 km N of Charlotte Amalie, U.S. Virgin Islands · 50 km SW of this epicentre
  4. 5.0 127 km NNE of Cruz Bay, U.S. Virgin Islands · 32 km S 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 19.7386, -64.5833. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.9 131 km N of Cruz Bay, U.S. Virgin Islands
  2. 3.8 135 km N of Cruz Bay, U.S. Virgin Islands
  3. 3.9 153 km N of Cruz Bay, U.S. Virgin Islands
  4. 3.6 140 km N of Charlotte Amalie, U.S. Virgin Islands
  5. 3.9 Virgin Islands
  6. 3.8 163 km NNE of Cruz Bay, U.S. Virgin Islands
  7. 3.8 136 km N of Charlotte Amalie, U.S. Virgin Islands
  8. 3.6 151 km N of Cruz Bay, U.S. Virgin Islands
  9. 3.7 142 km N of Charlotte Amalie, U.S. Virgin Islands
  10. 3.4 145 km NNE of Cruz Bay, U.S. Virgin Islands
  11. 3.9 Virgin Islands
  12. 3.8 166 km NNE of Cruz Bay, U.S. Virgin Islands
  13. 3.7 136 km N of Cruz Bay, U.S. Virgin Islands
  14. 3.8 168 km NNE of Cruz Bay, U.S. Virgin Islands
  15. 4.0 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.