QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0md

Earthquake near Arecibo, PR

No earthquake was likely felt in Arecibo in the 24 hours to 3:34 pm AST (19:34 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 3.0 earthquake was recorded 20 km (12 mi) north of Arecibo, PR, at 7:05 pm AST on 9 October 2021 (23:05 UTC), 13 km deep.

USGS: Puerto Rico region

77 km (48 mi) WNW of San Juan, PR · 22 km (13 mi) N of Arecibo, PR

7:05 pm AST, Oct 9, 2021 · · 13 km deep · released about 990 lb of TNT

Every earthquake near Arecibo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Hatillo Municipio 24 kmArecibo Municipio 25 kmCamuy Municipio 26 kmQuebradillas Municipio 28 kmBarceloneta Municipio 28 kmIsabela Municipio 33 kmManatí Municipio 35 kmFlorida Municipio 37 kmSan Sebastián Municipio 42 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
7:05 pm AST on 9 October 2021 ()
Where
20 km (12 mi) north of Arecibo, PR · earthquakes near Arecibo
Magnitude
M 3.0 (md)
Depth
13 km below the surface
Felt
no reports yet
Nearest
Hatillo Municipio, 24 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1859 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 35 km (22 mi) from the epicentre. In Arecibo, 20 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: Hatillo 20 km, intensity II · Arecibo 20 km, intensity II · Quebradillas 28 km, intensity II · Barceloneta 31 km, intensity II · Isabela 33 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 990 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 340,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 15,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 990 lb of TNT

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 4.4 on 2018-12-09 — about 120 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 18.6496, -66.7508. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Hatillo Municipio, PR 24 km (15 mi) SSW earthquakes near Hatillo Municipio
Arecibo Municipio, PR 25 km (16 mi) SSE earthquakes near Arecibo Municipio
Camuy Municipio, PR 26 km (16 mi) SSW earthquakes near Camuy Municipio
Quebradillas Municipio, PR 28 km (17 mi) SW earthquakes near Quebradillas Municipio
Barceloneta Municipio, PR 28 km (18 mi) SE earthquakes near Barceloneta Municipio
Isabela Municipio, PR 33 km (21 mi) WSW earthquakes near Isabela Municipio

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

Aftershocks so far

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

  1. 3.5 65 km N of Arecibo, Puerto Rico
  2. 2.6 23 km NNE of Isabela, Puerto Rico
  3. 2.1 18 km NNE of Carrizales, Puerto Rico
  4. 2.9 13 km N of Brenas, Puerto Rico
  5. 3.1 52 km N of Carrizales, Puerto Rico
  6. 3.0 42 km N of Tierras Nuevas Poniente, Puerto Rico
  7. 2.1 2 km ESE of Moca, Puerto Rico
  8. 3.4 28 km N of Arecibo, Puerto Rico
  9. 3.4 48 km N of Isabela, Puerto Rico
  10. 3.0 16 km N of Camuy, Puerto Rico
  11. 2.3 10 km SSE of Lares, Puerto Rico
  12. 2.6 25 km N of Garrochales, Puerto Rico
  13. 2.7 13 km NNW of Camuy, Puerto Rico
  14. 3.0 51 km N of Isabela, Puerto Rico
  15. 3.0 19 km N of Camuy, 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.