QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3md

Earthquake near Guaynabo, PR

No earthquake was likely felt in Guaynabo in the 24 hours to 12:49 pm AST (16:49 UTC). The last one was M 4.1, 93 km (58 mi) ESE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near Guaynabo

This page: a magnitude 3.3 earthquake was recorded 4 km (3 mi) east-northeast of Guaynabo, PR, at 7:38 am AST on 22 September 2023 (11:38 UTC), 109 km deep. 1 person has reported feeling it to USGS.

USGS: 4 km ENE of Guaynabo, Puerto Rico

in San Juan, PR

7:38 am AST, Sep 22, 2023 · · 109 km deep · released about 1.3 tons of TNT

Every earthquake near Guaynabo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Guaynabo Municipio 5 kmSan Juan Municipio 6 kmTrujillo Alto Municipio 8 kmBayamón Municipio 11 kmCarolina Municipio 11 kmCataño Municipio 12 kmAguas Buenas Municipio 14 kmGurabo Municipio 14 kmLoíza Municipio 16 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
7:38 am AST on 22 September 2023 ()
Where
4 km (3 mi) east-northeast of Guaynabo, PR · earthquakes near Guaynabo
Magnitude
M 3.3 (md)
Depth
109 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Guaynabo Municipio, 5 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1075 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 Guaynabo, 4 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.

Earthquakes near other towns within 30 km: Eleanor Roosevelt, Trujillo Alto, Bayamón, Cataño, San Juan, Carolina.

How big was it?

This earthquake released about 1.3 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 6.7 130,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 6,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,300× the energy of this one
  4. This earthquake M 3.3 about 1.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.6× 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 since 2016 was M 4.6 on 2019-03-12 — about 95 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.1 3 km W of Aguas Buenas, Puerto Rico · 14 km SSW of this epicentre
  2. 5.0 3 km N of Brenas, Puerto Rico · 32 km WNW 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 18.3672, -66.0703. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Guaynabo Municipio, PR 5 km (3 mi) WSW earthquakes near Guaynabo Municipio
San Juan Municipio, PR 6 km (4 mi) N earthquakes near San Juan Municipio
Trujillo Alto Municipio, PR 8 km (5 mi) ESE earthquakes near Trujillo Alto Municipio
Bayamón Municipio, PR 11 km (7 mi) W earthquakes near Bayamón Municipio
Carolina Municipio, PR 11 km (7 mi) ENE earthquakes near Carolina Municipio
Cataño Municipio, PR 12 km (7 mi) NW earthquakes near Cataño Municipio

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

Aftershocks so far

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

  1. 1.8 6 km SSW of Orocovis, Puerto Rico
  2. 2.3 8 km SSW of Orocovis, Puerto Rico
  3. 3.3 Puerto Rico region
  4. 2.1 7 km NNW of Coamo, Puerto Rico
  5. 3.0 24 km NNW of Loíza, Puerto Rico
  6. 2.5 2 km SSE of Caguas, Puerto Rico
  7. 2.0 Puerto Rico region
  8. 2.1 Puerto Rico region
  9. 3.4 8 km S of Orocovis, Puerto Rico
  10. 2.8 1 km SSW of Cidra, Puerto Rico
  11. 2.3 Puerto Rico region
  12. 3.2 2 km NNW of San Juan, 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.