QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7md

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

Yes. A magnitude 3.7 earthquake was recorded 88 km N of Cruz Bay, U.S. Virgin Islands, at 6:14 pm AST on 8 February 2021 (22:14 UTC), 35 km deep.

· 35 km deep · released about 5.5 tons of TNT

10 km30 km60 km120 km N Culebra Municipio 113 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
35 km below the surface
Felt
no reports yet
Nearest
Culebra Municipio, 113 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2029 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 68 km (42 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 5.5 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 31,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 970× the energy of this one
  4. This earthquake M 3.7 about 5.5 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 12× 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 2021-02-06 — about 83 times the energy of this one.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 131 km NNE of Cruz Bay, U.S. Virgin Islands · 43 km NNE of this epicentre
  2. 6.1 91 km N of Charlotte Amalie, U.S. Virgin Islands · 21 km WNW of this epicentre
  3. 6.0 112 km N of Charlotte Amalie, U.S. Virgin Islands · 40 km NW of this epicentre
  4. 5.9 68 km N of Cruz Bay, U.S. Virgin Islands · 21 km SSW of this epicentre
  5. 5.9 65 km NNE of Cruz Bay, U.S. Virgin Islands · 27 km SSE 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 19.1216, -64.6385. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Culebra Municipio, PR 113 km (70 mi) SW earthquakes near Culebra Municipio
Fajardo Municipio, PR 129 km (80 mi) SW earthquakes near Fajardo Municipio
Vieques Municipio, PR 139 km (86 mi) SW earthquakes near Vieques Municipio
Luquillo Municipio, PR 141 km (87 mi) SW earthquakes near Luquillo Municipio
Ceiba Municipio, PR 142 km (88 mi) SW earthquakes near Ceiba Municipio
Naguabo Municipio, PR 154 km (95 mi) SW earthquakes near Naguabo 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. 3.6 Virgin Islands
  2. 2.6 Virgin Islands
  3. 3.4 Virgin Islands
  4. 3.8 114 km NNE of Cruz Bay, U.S. Virgin Islands
  5. 3.8 83 km NE of Cruz Bay, U.S. Virgin Islands
  6. 4.0 126 km NNE of Cruz Bay, U.S. Virgin Islands
  7. 3.9 123 km NNE of Cruz Bay, U.S. Virgin Islands
  8. 3.9 112 km NNE of Cruz Bay, U.S. Virgin Islands
  9. 3.6 52 km NNE of Cruz Bay, U.S. Virgin Islands
  10. 3.7 93 km NNE of Cruz Bay, U.S. Virgin Islands
  11. 3.7 93 km N of Charlotte Amalie, U.S. Virgin Islands
  12. 3.3 92 km N of Charlotte Amalie, U.S. Virgin Islands
  13. 3.5 108 km N of Charlotte Amalie, U.S. Virgin Islands
  14. 4.0 120 km N of Cruz Bay, U.S. Virgin Islands
  15. 2.9 42 km NNE 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.