QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5md

Earthquake near Dorado, PR

No earthquake was likely felt in Dorado in the 24 hours to 1:35 pm AST (17:35 UTC). The last one was M 4.8, 92 km (57 mi) SW, at 9:19 am AST on 18 September 2026, estimated intensity III (weak) in town; 86 felt reports to USGS. Every earthquake near Dorado

This page: a magnitude 3.5 earthquake was recorded in Dorado, PR, at 3:45 am AST on 22 August 2021 (07:45 UTC), 99 km deep. 2 people have reported feeling it to USGS.

USGS: 1 km ENE of Dorado, Puerto Rico

21 km (13 mi) WNW of San Juan, PR · 14 km (8 mi) NW of Bayamón, PR

3:45 am AST, Aug 22, 2021 · · 99 km deep · released about 2.8 tons of TNT

Every earthquake near Dorado Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Dorado Municipio 1 kmToa Baja Municipio 7 kmVega Alta Municipio 9 kmToa Alta Municipio 11 kmCataño Municipio 12 kmVega Baja Municipio 15 kmBayamón Municipio 16 kmCorozal Municipio 19 kmNaranjito Municipio 19 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
3:45 am AST on 22 August 2021 ()
Where
in Dorado, PR · earthquakes near Dorado
Magnitude
M 3.5 (md)
Depth
99 km below the surface
Felt
2 reports · strongest reported intensity IV
Measured shaking
intensity II (ShakeMap)
Nearest
Dorado Municipio, 1 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1835 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 it was probably too small to be felt, even directly above it. 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.

Earthquakes near other towns within 30 km: Toa Baja, Ingenio, San Antonio, Campanilla, Candelaria Arenas, San José.

How big was it?

This earthquake released about 2.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 61,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,700× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,900× the energy of this one
  4. This earthquake M 3.5 about 2.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 5.8× 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 4.4 on 2018-12-09 — about 22 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.8 12 km N of Garrochales, Puerto Rico · 34 km WNW of this epicentre
  2. 5.1 3 km W of Aguas Buenas, Puerto Rico · 26 km SSE of this epicentre
  3. 5.0 3 km N of Brenas, Puerto Rico · 10 km WNW 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 18.4628, -66.2571. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Dorado Municipio, PR 1 km (1 mi) NNW earthquakes near Dorado Municipio
Toa Baja Municipio, PR 7 km (4 mi) E earthquakes near Toa Baja Municipio
Vega Alta Municipio, PR 9 km (6 mi) WSW earthquakes near Vega Alta Municipio
Toa Alta Municipio, PR 11 km (7 mi) S earthquakes near Toa Alta Municipio
Cataño Municipio, PR 12 km (7 mi) E earthquakes near Cataño Municipio
Vega Baja Municipio, PR 15 km (9 mi) W earthquakes near Vega Baja Municipio

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

Aftershocks so far

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

  1. 3.6 2 km ESE of Pájaros, Puerto Rico
  2. 3.3 1 km SW of Cayey, Puerto Rico
  3. 2.8 1 km SSW of Cayey, Puerto Rico
  4. 3.0 2 km SW of Canovanas, Puerto Rico
  5. 2.0 5 km S of Morovis, Puerto Rico
  6. 2.7 0 km NW of Aguas Buenas, Puerto Rico
  7. 2.7 2 km W of Pastos, Puerto Rico
  8. 2.8 12 km N of San Juan, Puerto Rico
  9. 2.9 0 km WNW of Aguas Buenas, Puerto Rico
  10. 3.1 13 km N of Levittown, Puerto Rico
  11. 3.0 35 km N of Tierras Nuevas Poniente, Puerto Rico
  12. 2.8 5 km SSE of Corozal, Puerto Rico
  13. 3.2 3 km S of Guaynabo, Puerto Rico
  14. 2.5 3 km S of Barranquitas, Puerto Rico
  15. 3.2 38 km N of San Juan, 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.