QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6md

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 8:30 am AST (12:30 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 3.6 earthquake was recorded 48 km (30 mi) northeast of San Juan, PR, at 6:19 am AST on 30 July 2023 (10:19 UTC), 79 km deep.

USGS: 43 km N of Suárez, Puerto Rico

52 km (32 mi) NNE of San Juan, PR · 48 km (30 mi) NNE of Carolina, PR

6:19 am AST, Jul 30, 2023 · · 79 km deep · released about 3.4 tons of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 43 kmCarolina Municipio 49 kmRío Grande Municipio 50 kmSan Juan Municipio 50 kmLuquillo Municipio 53 kmCataño Municipio 53 kmToa Baja Municipio 55 kmCanóvanas Municipio 55 kmFajardo Municipio 56 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
6:19 am AST on 30 July 2023 ()
Where
48 km (30 mi) northeast of San Juan, PR · earthquakes near San Juan
Magnitude
M 3.6 (md)
Depth
79 km below the surface
Felt
no reports yet
Nearest
Loíza Municipio, 43 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1200 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 3.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 50,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,200× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,600× the energy of this one
  4. This earthquake M 3.6 about 3.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.2× 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.0 73 km NNE of Vieques, Puerto Rico · 42 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 18.8226, -65.8445. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 43 km (27 mi) SSW earthquakes near Loíza Municipio
Carolina Municipio, PR 49 km (31 mi) SSW earthquakes near Carolina Municipio
Río Grande Municipio, PR 50 km (31 mi) S earthquakes near Río Grande Municipio
San Juan Municipio, PR 50 km (31 mi) SSW earthquakes near San Juan Municipio
Luquillo Municipio, PR 53 km (33 mi) SSE earthquakes near Luquillo Municipio
Cataño Municipio, PR 53 km (33 mi) SW earthquakes near Cataño Municipio

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

Aftershocks so far

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

  1. 3.3 29 km NNE of Suárez, Puerto Rico
  2. 2.9 68 km NNE of Luquillo, Puerto Rico
  3. 3.2 55 km N of Loíza, Puerto Rico
  4. 3.5 59 km N of Culebra, Puerto Rico
  5. 3.2 67 km N of San Juan, Puerto Rico
  6. 3.2 64 km N of San Juan, Puerto Rico
  7. 3.4 75 km N of San Juan, Puerto Rico
  8. 3.3 78 km N of Suárez, Puerto Rico
  9. 3.2 50 km N of Suárez, Puerto Rico
  10. 3.6 63 km NNE of Vieques, Puerto Rico
  11. 3.1 65 km N of San Juan, Puerto Rico
  12. 3.2 71 km N of San Juan, Puerto Rico
  13. 3.9 52 km N of Suárez, Puerto Rico
  14. 3.1 61 km N of Brenas, Puerto Rico
  15. 3.5 70 km NNE of Luquillo, 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.