QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7md

65 km ENE of Cruz Bay, U.S. Virgin Islands

Yes. A magnitude 3.7 earthquake was recorded 65 km ENE of Cruz Bay, U.S. Virgin Islands, at 2:41 pm AST on 4 August 2018 (18:41 UTC), 109 km deep.

· 109 km deep · released about 5 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Culebra Municipio 119 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 3.7 (md)
Depth
109 km below the surface
Felt
no reports yet
Nearest
Culebra Municipio, 119 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2948 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 it was probably too small to be felt, even directly above it. 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 5 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 34,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,500× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,100× the energy of this one
  4. This earthquake M 3.7 about 5 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 10× 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 4.2 on 2017-11-11 — about 6 times the energy of this one.

Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.

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 18.4786, -64.1893. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Culebra Municipio, PR 119 km (74 mi) W earthquakes near Culebra Municipio

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

Aftershocks so far

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

  1. 3.3 83 km ENE of Cruz Bay, U.S. Virgin Islands
  2. 3.1 33 km NNE of Cruz Bay, U.S. Virgin Islands
  3. 3.1 40 km ESE of Cruz Bay, U.S. Virgin Islands
  4. 3.2 52 km NNE of Cruz Bay, U.S. Virgin Islands
  5. 2.9 18 km ENE of Cruz Bay, U.S. Virgin Islands
  6. 3.0 86 km ENE of Cruz Bay, U.S. Virgin Islands
  7. 3.2 63 km NNE of Cruz Bay, U.S. Virgin Islands
  8. 3.3 78 km ENE of Cruz Bay, U.S. Virgin Islands
  9. 3.6 50 km E of Cruz Bay, U.S. Virgin Islands
  10. 3.4 61 km ENE of Cruz Bay, U.S. Virgin Islands
  11. 3.1 73 km E of Cruz Bay, U.S. Virgin Islands
  12. 3.0 34 km ENE of Cruz Bay, U.S. Virgin Islands
  13. 2.9 66 km NE of Cruz Bay, U.S. Virgin Islands
  14. 3.3 45 km NE of Cruz Bay, U.S. Virgin Islands
  15. 3.4 66 km NE 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.