QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6md

50 km NW of Rincón, Puerto Rico

Yes. A magnitude 3.6 earthquake was recorded 50 km NW of Rincón, Puerto Rico, at 6:19 pm AST on 12 April 2021 (22:19 UTC), 4.0 km deep. 4 people have reported feeling it to USGS.

· 4.0 km deep · released about 3.9 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Rincón Municipio 51 kmAguadilla Municipio 51 kmAguada Municipio 53 kmMoca Municipio 62 kmIsabela Municipio 64 kmAñasco Municipio 64 kmMayagüez Municipio 73 kmQuebradillas Municipio 73 kmSan Sebastián Municipio 75 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 3.6 (md)
Depth
4.0 km below the surface
Felt
4 reports · strongest reported intensity II
Nearest
Rincón Municipio, 51 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1971 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 3.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 43,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,900× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,400× the energy of this one
  4. This earthquake M 3.6 about 3.9 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 8.2× 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 4.6 on 2020-01-29 — about 31 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 24 km NNW of San Antonio, Puerto Rico · 42 km E of this epicentre
  2. 6.4 32 km NW of Aguadilla, Puerto Rico · 22 km ESE of this epicentre
  3. 6.3 6 km WNW of Aguadilla, Puerto Rico · 47 km ESE of this epicentre
  4. 6.3 58 km E of Punta Cana, Dominican Republic · 35 km WSW of this epicentre
  5. 6.1 15 km WNW of San Antonio, Puerto Rico · 39 km ESE 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 18.6713, -67.5841. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Rincón Municipio, PR 51 km (32 mi) SE earthquakes near Rincón Municipio
Aguadilla Municipio, PR 51 km (32 mi) ESE earthquakes near Aguadilla Municipio
Aguada Municipio, PR 53 km (33 mi) SE earthquakes near Aguada Municipio
Moca Municipio, PR 62 km (39 mi) ESE earthquakes near Moca Municipio
Isabela Municipio, PR 64 km (40 mi) ESE earthquakes near Isabela Municipio
Añasco Municipio, PR 64 km (40 mi) SE earthquakes near Añasco Municipio

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

Aftershocks so far

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

  1. 3.2 31 km WNW of Rincón, Puerto Rico
  2. 3.2 48 km NNW of San Antonio, Puerto Rico
  3. 3.0 11 km NNW of Rincón, Puerto Rico
  4. 3.1 7 km WNW of Aguadilla, Puerto Rico
  5. 3.0 14 km NW of Rincón, Puerto Rico
  6. 3.1 57 km WNW of Rincón, Puerto Rico
  7. 3.5 51 km NNW of San Antonio, Puerto Rico
  8. 3.4 70 km ENE of Punta Cana, Dominican Republic
  9. 3.1 86 km NE of Punta Cana, Dominican Republic
  10. 3.0 25 km NNW of Rincón, Puerto Rico
  11. 3.2 87 km NW of San Antonio, Puerto Rico
  12. 3.4 34 km NW of San Antonio, Puerto Rico
  13. 3.3 44 km NW of Aguadilla, Puerto Rico
  14. 3.2 45 km NW of Aguadilla, Puerto Rico
  15. 3.9 56 km WNW of Rincón, 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.