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 4:43 pm AST (20:43 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 47 km (29 mi) southwest of San Juan, PR, at 2:40 pm AST on 30 September 2023 (18:40 UTC), 5.0 km deep. 4 people have reported feeling it to USGS.

USGS: 8 km S of Orocovis, Puerto Rico

45 km (28 mi) SW of San Juan, PR · 29 km (18 mi) NE of Ponce, PR

2:40 pm AST, Sep 30, 2023 · · 5.0 km deep · released about 1.8 tons of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Coamo Municipio 6 kmVillalba Municipio 8 kmOrocovis Municipio 9 kmBarranquitas Municipio 11 kmAibonito Municipio 14 kmCorozal Municipio 19 kmMorovis Municipio 19 kmJuana Díaz Municipio 20 kmComerío Municipio 20 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
2:40 pm AST on 30 September 2023 ()
Where
47 km (29 mi) southwest of San Juan, PR · earthquakes near San Juan
Magnitude
M 3.4 (md)
Depth
5.0 km below the surface
Felt
4 reports · strongest reported intensity IV
Nearest
Coamo Municipio, 6 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1068 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 56 km (35 mi) from the epicentre. In San Juan, 47 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: Coamo 9 km, intensity III · Río Cañas Abajo 15 km, intensity III · Santa Isabel 20 km, intensity III · Jayuya 22 km, intensity III · Ciales 22 km, intensity III · Corozal 23 km, intensity III · Cayey 25 km, intensity II · Ponce 29 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.8 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 95,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,300× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,000× the energy of this one
  4. This earthquake M 3.4 about 1.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3.7× 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 6.4 on 2020-01-07 — about 34,000 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 · 49 km NNW of this epicentre
  2. 5.1 3 km W of Aguas Buenas, Puerto Rico · 30 km ENE of this epicentre
  3. 5.0 3 km N of Brenas, Puerto Rico · 39 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 18.1496, -66.3948. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Coamo Municipio, PR 6 km (4 mi) SE earthquakes near Coamo Municipio
Villalba Municipio, PR 8 km (5 mi) WSW earthquakes near Villalba Municipio
Orocovis Municipio, PR 9 km (6 mi) NNW earthquakes near Orocovis Municipio
Barranquitas Municipio, PR 11 km (7 mi) ENE earthquakes near Barranquitas Municipio
Aibonito Municipio, PR 14 km (9 mi) E earthquakes near Aibonito Municipio
Corozal Municipio, PR 19 km (12 mi) NNE earthquakes near Corozal Municipio

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

Aftershocks so far

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

  1. 2.2 Puerto Rico region
  2. 2.6 0 km NE of Yauco, Puerto Rico
  3. 2.5 2 km S of Magas Arriba, Puerto Rico
  4. 2.2 4 km WSW of Tallaboa, Puerto Rico
  5. 2.0 Puerto Rico region
  6. 2.7 Puerto Rico region
  7. 2.1 Puerto Rico region
  8. 3.3 4 km SSE of Salinas, Puerto Rico
  9. 3.2 Puerto Rico region

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.