QuakeIndex

Earthquake · reviewed by a seismologist

M 3.2md

94 km NW of San Antonio, Puerto Rico

Yes. A magnitude 3.2 earthquake was recorded 94 km NW of San Antonio, Puerto Rico, at 3:31 pm AST on 20 August 2021 (19:31 UTC), 23 km deep.

· 23 km deep · released about 1,700 lb of TNT

10 km30 km60 km120 km N Aguadilla Municipio 93 kmAguada Municipio 100 kmRincón Municipio 101 kmIsabela Municipio 102 kmMoca Municipio 106 kmQuebradillas Municipio 109 kmAñasco Municipio 112 kmCamuy Municipio 116 kmSan Sebastián Municipio 118 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 3.2 (md)
Depth
23 km below the surface
Felt
no reports yet
Nearest
Aguadilla Municipio, 93 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1909 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. 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 1,700 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 200,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 8,800× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,200× the energy of this one
  4. This earthquake M 3.2 about 1,700 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.8× 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 6.0 on 2019-09-24 — about 18,000 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. 6.8 94 km NE of Punta Cana, Dominican Republic · 4 km WSW of this epicentre
  2. 6.1 80 km NE of Punta Cana, Dominican Republic · 23 km W of this epicentre
  3. 6.0 93 km NNW of San Antonio, Puerto Rico · 45 km ENE of this epicentre
  4. 6.0 67 km NNW of San Antonio, Puerto Rico · 45 km E of this epicentre
  5. 5.7 88 km N of San Antonio, Puerto Rico · 48 km ENE 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 19.1473, -67.6790. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aguadilla Municipio, PR 93 km (58 mi) SE earthquakes near Aguadilla Municipio
Aguada Municipio, PR 100 km (62 mi) SSE earthquakes near Aguada Municipio
Rincón Municipio, PR 101 km (62 mi) SSE earthquakes near Rincón Municipio
Isabela Municipio, PR 102 km (63 mi) SE earthquakes near Isabela Municipio
Moca Municipio, PR 106 km (66 mi) SE earthquakes near Moca Municipio
Quebradillas Municipio, PR 109 km (68 mi) SE earthquakes near Quebradillas Municipio

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

Aftershocks so far

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

  1. 3.5 84 km NNW of San Antonio, Puerto Rico
  2. 3.4 91 km NNE of Punta Cana, Dominican Republic
  3. 3.1 59 km NW of San Antonio, Puerto Rico
  4. 3.4 60 km NW of San Antonio, Puerto Rico
  5. 3.5 84 km NNW of San Antonio, Puerto Rico
  6. 3.5 79 km N of San Antonio, Puerto Rico
  7. 3.5 98 km NE of Punta Cana, Dominican Republic
  8. 3.8 88 km NNW of San Antonio, Puerto Rico
  9. 3.6 93 km NNW of San Antonio, Puerto Rico
  10. 3.5 67 km N of San Antonio, Puerto Rico
  11. 3.6 80 km NNW of San Antonio, Puerto Rico
  12. 3.0 89 km NE of Punta Cana, Dominican Republic
  13. 3.4 89 km NE of Punta Cana, Dominican Republic
  14. 3.4 75 km NW of Aguadilla, Puerto Rico
  15. 3.5 121 km NE of Punta Cana, Dominican Republic

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.