QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3md

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 1:07 am AST (05:07 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 3.3 earthquake was recorded 30 km (19 mi) west-southwest of San Juan, PR, at 7:35 pm AST on 7 September 2023 (23:35 UTC), 121 km deep. 1 person has reported feeling it to USGS.

USGS: Puerto Rico region

33 km (20 mi) W of San Juan, PR · 22 km (14 mi) W of Bayamón, PR

7:35 pm AST, Sep 7, 2023 · · 121 km deep · released about 1.4 tons of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Morovis Municipio 7 kmCorozal Municipio 8 kmVega Alta Municipio 9 kmVega Baja Municipio 11 kmToa Alta Municipio 13 kmNaranjito Municipio 15 kmManatí Municipio 16 kmDorado Municipio 17 kmCiales Municipio 17 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
7:35 pm AST on 7 September 2023 ()
Where
30 km (19 mi) west-southwest of San Juan, PR · earthquakes near San Juan
Magnitude
M 3.3 (md)
Depth
121 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Morovis Municipio, 7 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1161 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, 30 km away, the estimate is intensity I (not felt). 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: Miranda, Morovis, Corozal, Vega Alta, Franquez, Monserrate.

How big was it?

This earthquake released about 1.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 120,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,800× the energy of this one
  4. This earthquake M 3.3 about 1.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.9× 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.

Where

Epicentre 18.3642, -66.3693. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Morovis Municipio, PR 7 km (5 mi) SW earthquakes near Morovis Municipio
Corozal Municipio, PR 8 km (5 mi) SE earthquakes near Corozal Municipio
Vega Alta Municipio, PR 9 km (5 mi) NNE earthquakes near Vega Alta Municipio
Vega Baja Municipio, PR 11 km (7 mi) NNW earthquakes near Vega Baja Municipio
Toa Alta Municipio, PR 13 km (8 mi) E earthquakes near Toa Alta Municipio
Naranjito Municipio, PR 15 km (9 mi) SE earthquakes near Naranjito Municipio

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

Aftershocks so far

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

  1. 2.3 5 km SSE of Salinas, Puerto Rico
  2. 2.4 3 km SSE of Salinas, Puerto Rico
  3. 2.3 Puerto Rico region
  4. 3.3 4 km ENE of Guaynabo, Puerto Rico
  5. 2.6 8 km S of Orocovis, Puerto Rico
  6. 2.3 3 km S of Las Ochenta, Puerto Rico
  7. 2.4 4 km WSW of Central Aguirre, Puerto Rico
  8. 2.5 Puerto Rico region
  9. 2.7 4 km S of Salinas, Puerto Rico
  10. 2.3 4 km SSE of Salinas, Puerto Rico
  11. 1.9 Puerto Rico region
  12. 2.3 1 km SSW of Ponce, Puerto Rico
  13. 2.4 0 km WSW of Ponce, 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.