QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 12:48 pm AST (16:48 UTC). The last one was M 4.1, 99 km (62 mi) SE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near San Juan

This page: a magnitude 3.1 earthquake was recorded 48 km (30 mi) northwest of San Juan, PR, at 11:35 am AST on 25 June 2021 (15:35 UTC), 59 km deep.

USGS: 35 km NNW of Brenas, Puerto Rico

56 km (35 mi) NW of San Juan, PR · 49 km (30 mi) NE of Arecibo, PR

11:35 am AST, Jun 25, 2021 · · 59 km deep · released about 1,300 lb of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Vega Baja Municipio 36 kmBarceloneta Municipio 37 kmDorado Municipio 38 kmManatí Municipio 38 kmVega Alta Municipio 39 kmToa Baja Municipio 43 kmArecibo Municipio 47 kmCataño Municipio 47 kmFlorida Municipio 48 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
11:35 am AST on 25 June 2021 ()
Where
48 km (30 mi) northwest of San Juan, PR · earthquakes near San Juan
Magnitude
M 3.1 (md)
Depth
59 km below the surface
Felt
no reports yet
Nearest
Vega Baja Municipio, 36 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1965 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. In San Juan, 48 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.

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 6.7 250,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,900× 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 1.4× 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 4.8 on 2017-08-18 — about 350 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 78 km N of Arecibo, Puerto Rico · 50 km NNW of this epicentre
  2. 5.8 12 km N of Garrochales, Puerto Rico · 28 km SSW of this epicentre
  3. 5.7 78 km N of Tierras Nuevas Poniente, Puerto Rico · 45 km NNW of this epicentre
  4. 5.5 64 km N of Tierras Nuevas Poniente, Puerto Rico · 30 km NNW of this epicentre
  5. 5.1 66 km N of Brenas, Puerto Rico · 33 km N 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 18.7808, -66.4228. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Vega Baja Municipio, PR 36 km (23 mi) S earthquakes near Vega Baja Municipio
Barceloneta Municipio, PR 37 km (23 mi) SSW earthquakes near Barceloneta Municipio
Dorado Municipio, PR 38 km (24 mi) SSE earthquakes near Dorado Municipio
Manatí Municipio, PR 38 km (24 mi) S earthquakes near Manatí Municipio
Vega Alta Municipio, PR 39 km (24 mi) SSE earthquakes near Vega Alta Municipio
Toa Baja Municipio, PR 43 km (27 mi) SE earthquakes near Toa Baja 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. 2.3 59 km N of Tierras Nuevas Poniente, Puerto Rico
  2. 3.0 67 km N of Tierras Nuevas Poniente, Puerto Rico
  3. 3.2 Puerto Rico region
  4. 3.5 58 km N of Hatillo, Puerto Rico
  5. 3.5 40 km N of Carrizales, Puerto Rico
  6. 3.6 63 km N of Hatillo, Puerto Rico
  7. 3.1 Puerto Rico region
  8. 3.4 50 km N of Brenas, Puerto Rico
  9. 3.5 72 km N of Brenas, Puerto Rico
  10. 3.4 65 km N of Brenas, Puerto Rico
  11. 3.3 72 km N of Brenas, Puerto Rico
  12. 3.5 57 km N of San Juan, Puerto Rico
  13. 2.8 12 km N of San Juan, Puerto Rico
  14. 3.3 26 km N of Hatillo, Puerto Rico
  15. 3.0 15 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.