QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 10:04 pm AST (02:04 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 3.4 earthquake was recorded 42 km (26 mi) north of San Juan, PR, at 4:17 pm AST on 22 April 2023 (20:17 UTC), 28 km deep. 1 person has reported feeling it to USGS.

USGS: Puerto Rico region

48 km (30 mi) N of San Juan, PR

4:17 pm AST, Apr 22, 2023 · · 28 km deep · released about 1.7 tons of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Toa Baja Municipio 44 kmCataño Municipio 45 kmDorado Municipio 45 kmLoíza Municipio 46 kmSan Juan Municipio 47 kmCarolina Municipio 51 kmVega Alta Municipio 52 kmVega Baja Municipio 54 kmGuaynabo Municipio 55 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
4:17 pm AST on 22 April 2023 ()
Where
42 km (26 mi) north of San Juan, PR · earthquakes near San Juan
Magnitude
M 3.4 (md)
Depth
28 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Toa Baja Municipio, 44 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1299 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 49 km (30 mi) from the epicentre. In San Juan, 42 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: San Juan 42 km, intensity II · Cataño 45 km, intensity II · Levittown 45 km, intensity II · Dorado 47 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 99,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,100× the energy of this one
  4. This earthquake M 3.4 about 1.7 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3.6× 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 in our catalogue was M 4.8 on 2017-08-18 — about 140 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 18.8403, -66.0798. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Toa Baja Municipio, PR 44 km (28 mi) SSW earthquakes near Toa Baja Municipio
Cataño Municipio, PR 45 km (28 mi) S earthquakes near Cataño Municipio
Dorado Municipio, PR 45 km (28 mi) SSW earthquakes near Dorado Municipio
Loíza Municipio, PR 46 km (29 mi) SSE earthquakes near Loíza Municipio
San Juan Municipio, PR 47 km (29 mi) S earthquakes near San Juan Municipio
Carolina Municipio, PR 51 km (31 mi) SSE earthquakes near Carolina Municipio

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

Aftershocks so far

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

  1. 2.5 39 km N of Tierras Nuevas Poniente, Puerto Rico
  2. 3.3 Puerto Rico region
  3. 3.1 52 km N of Brenas, Puerto Rico
  4. 3.4 52 km N of Brenas, Puerto Rico
  5. 3.2 55 km N of Brenas, Puerto Rico
  6. 3.0 24 km NNW of Loíza, Puerto Rico
  7. 3.2 Puerto Rico region
  8. 3.2 2 km NNW of San Juan, Puerto Rico
  9. 3.0 57 km NNE of San Juan, Puerto Rico
  10. 3.6 69 km N of Suárez, Puerto Rico
  11. 2.8 5 km NNW of Brenas, Puerto Rico
  12. 3.0 56 km N of Dorado, Puerto Rico
  13. 3.2 6 km N of San Juan, Puerto Rico
  14. 3.0 Puerto Rico region
  15. 3.6 43 km N of Suárez, 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.