QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near Arecibo, PR

No earthquake was likely felt in Arecibo in the 24 hours to 10:04 pm AST (02:04 UTC). The last one was M 3.4, 49 km (31 mi) NW, at 9:00 pm AST on 27 October 2026, estimated intensity II (weak) in town. Every earthquake near Arecibo

This page: a magnitude 3.1 earthquake was recorded 33 km (20 mi) north of Arecibo, PR, at 6:27 pm AST on 11 December 2021 (22:27 UTC), 13 km deep.

USGS: Puerto Rico region

76 km (47 mi) WNW of San Juan, PR · 35 km (22 mi) N of Arecibo, PR

6:27 pm AST, Dec 11, 2021 · · 13 km deep · released about 1,300 lb of TNT

Every earthquake near Arecibo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Barceloneta Municipio 35 kmArecibo Municipio 37 kmHatillo Municipio 38 kmCamuy Municipio 40 kmManatí Municipio 41 kmQuebradillas Municipio 42 kmVega Baja Municipio 46 kmFlorida Municipio 46 kmIsabela Municipio 47 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
6:27 pm AST on 11 December 2021 ()
Where
33 km (20 mi) north of Arecibo, PR · earthquakes near Arecibo
Magnitude
M 3.1 (md)
Depth
13 km below the surface
Felt
no reports yet
Nearest
Barceloneta Municipio, 35 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1721 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 39 km (24 mi) from the epicentre. In Arecibo, 33 km away, the estimate is intensity II (weak). 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.

Likely felt in: Arecibo 33 km, intensity II · Hatillo 35 km, intensity II · Barceloneta 38 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 270,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 12,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 8,500× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.3× 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 4.8 on 2017-08-18 — about 380 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 18.7650, -66.6803. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Barceloneta Municipio, PR 35 km (22 mi) SSE earthquakes near Barceloneta Municipio
Arecibo Municipio, PR 37 km (23 mi) S earthquakes near Arecibo Municipio
Hatillo Municipio, PR 38 km (24 mi) SSW earthquakes near Hatillo Municipio
Camuy Municipio, PR 40 km (25 mi) SSW earthquakes near Camuy Municipio
Manatí Municipio, PR 41 km (25 mi) SSE earthquakes near Manatí Municipio
Quebradillas Municipio, PR 42 km (26 mi) SW earthquakes near Quebradillas Municipio

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

Aftershocks so far

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

  1. 3.4 72 km N of Tierras Nuevas Poniente, Puerto Rico
  2. 3.3 68 km N of Tierras Nuevas Poniente, Puerto Rico
  3. 3.3 64 km N of Tierras Nuevas Poniente, Puerto Rico
  4. 2.9 20 km NNE of Carrizales, Puerto Rico
  5. 3.1 77 km N of Arecibo, Puerto Rico
  6. 3.1 61 km N of Brenas, Puerto Rico
  7. 2.3 9 km N of Animas, Puerto Rico
  8. 3.1 28 km N of Arecibo, Puerto Rico
  9. 3.3 46 km N of Arecibo, Puerto Rico
  10. 3.0 4 km N of Animas, Puerto Rico
  11. 3.1 53 km N of Tierras Nuevas Poniente, Puerto Rico
  12. 3.5 65 km N of Arecibo, Puerto Rico
  13. 4.1 72 km N of Arecibo, Puerto Rico
  14. 2.6 23 km NNE of Isabela, Puerto Rico
  15. 2.1 18 km NNE of Carrizales, Puerto Rico

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.