QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7md

44 km NNE of Cruz Bay, U.S. Virgin Islands

Yes. A magnitude 3.7 earthquake was recorded 44 km NNE of Cruz Bay, U.S. Virgin Islands, at 11:04 pm AST on 23 December 2020 (03:04 UTC), 30 km deep. 5 people have reported feeling it to USGS.

· 30 km deep · released about 5.5 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Culebra Municipio 79 kmFajardo Municipio 103 kmVieques Municipio 103 kmCeiba Municipio 112 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 3.7 (md)
Depth
30 km below the surface
Felt
5 reports · strongest reported intensity II
Nearest
Culebra Municipio, 79 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2076 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 70 km (43 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 4.7 on 2018-04-06 — about 31 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 68 km N of Cruz Bay, U.S. Virgin Islands · 26 km N of this epicentre
  2. 5.9 65 km NNE of Cruz Bay, U.S. Virgin Islands · 22 km NNE of this epicentre
  3. 5.7 80 km NNE of Cruz Bay, U.S. Virgin Islands · 36 km NNE of this epicentre
  4. 5.3 78 km NNE of Cruz Bay, U.S. Virgin Islands · 34 km N of this epicentre
  5. 5.2 36 km NNE of Cruz Bay, U.S. Virgin Islands · 8 km SSW 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 18.7153, -64.6800. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Culebra Municipio, PR 79 km (49 mi) WSW earthquakes near Culebra Municipio
Fajardo Municipio, PR 103 km (64 mi) WSW earthquakes near Fajardo Municipio
Vieques Municipio, PR 103 km (64 mi) SW earthquakes near Vieques Municipio
Ceiba Municipio, PR 112 km (69 mi) WSW earthquakes near Ceiba Municipio
Luquillo Municipio, PR 115 km (72 mi) WSW earthquakes near Luquillo Municipio
Río Grande Municipio, PR 124 km (77 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

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

  1. 3.5 82 km N of Charlotte Amalie, U.S. Virgin Islands
  2. 3.7 90 km N of Cruz Bay, U.S. Virgin Islands
  3. 3.4 90 km N of Cruz Bay, U.S. Virgin Islands
  4. 3.5 86 km N of Charlotte Amalie, U.S. Virgin Islands
  5. 3.5 64 km N of Cruz Bay, U.S. Virgin Islands
  6. 2.7 72 km N of Charlotte Amalie, U.S. Virgin Islands
  7. 3.0 87 km N of Cruz Bay, U.S. Virgin Islands
  8. 3.4 80 km N of Charlotte Amalie, U.S. Virgin Islands
  9. 3.5 75 km N of Charlotte Amalie, U.S. Virgin Islands
  10. 3.4 44 km N of Charlotte Amalie, U.S. Virgin Islands
  11. 3.4 44 km N of Charlotte Amalie, U.S. Virgin Islands
  12. 3.3 Virgin Islands
  13. 3.9 37 km ENE of Cruz Bay, U.S. Virgin Islands
  14. 3.6 76 km N of Cruz Bay, U.S. Virgin Islands
  15. 3.4 54 km ENE 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.