QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9md

Virgin Islands

Yes. A magnitude 3.9 earthquake was recorded in the Virgin Islands, at 4:27 am AST on 27 July 2023 (08:27 UTC), 49 km deep.

· 49 km deep · released about 10 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Culebra Municipio 83 kmFajardo Municipio 102 kmVieques Municipio 108 kmCeiba Municipio 113 kmLuquillo Municipio 115 km
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
49 km below the surface
Felt
no reports yet
Nearest
Culebra Municipio, 83 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1138 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 73 km (45 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 10 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 17,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 760× the energy of this one
  3. Magna, Utah 2020 M 5.7 540× the energy of this one
  4. This earthquake M 3.9 about 10 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 21× 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 5.5 on 2022-05-08 — about 270 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 18.8553, -64.7525. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Culebra Municipio, PR 83 km (52 mi) SW earthquakes near Culebra Municipio
Fajardo Municipio, PR 102 km (64 mi) WSW earthquakes near Fajardo Municipio
Vieques Municipio, PR 108 km (67 mi) SW earthquakes near Vieques Municipio
Ceiba Municipio, PR 113 km (70 mi) SW earthquakes near Ceiba Municipio
Luquillo Municipio, PR 115 km (71 mi) WSW earthquakes near Luquillo Municipio
Río Grande Municipio, PR 122 km (76 mi) WSW earthquakes near Río Grande Municipio

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 3.5 Virgin Islands
  2. 3.8 90 km NNE of Cruz Bay, U.S. Virgin Islands
  3. 3.3 Virgin Islands
  4. 3.6 Virgin Islands
  5. 3.8 83 km NNE of Cruz Bay, U.S. Virgin Islands
  6. 3.6 72 km N of Charlotte Amalie, U.S. Virgin Islands
  7. 3.8 90 km N of Charlotte Amalie, U.S. Virgin Islands
  8. 3.6 102 km N of Cruz Bay, U.S. Virgin Islands
  9. 3.7 63 km NNE of Cruz Bay, U.S. Virgin Islands
  10. 3.4 76 km N of Charlotte Amalie, U.S. Virgin Islands
  11. 3.5 62 km N of Cruz Bay, U.S. Virgin Islands
  12. 3.9 57 km N of Cruz Bay, U.S. Virgin Islands
  13. 3.2 32 km N of Charlotte Amalie, U.S. Virgin Islands
  14. 3.5 96 km NNE of Cruz Bay, U.S. Virgin Islands
  15. 3.7 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.