QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near Trujillo Alto, PR

USGS: 7 km NNW of Trujillo Alto, Puerto Rico

in San Juan, PR

11:42 am AST, Oct 6, 2026 · · 113 km deep · released about 1,200 lb of TNT

Every earthquake near Trujillo Alto Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Juan Municipio 3 kmCarolina Municipio 8 kmTrujillo Alto Municipio 9 kmGuaynabo Municipio 10 kmLoíza Municipio 12 kmCataño Municipio 12 kmBayamón Municipio 15 kmToa Baja Municipio 17 kmGurabo Municipio 17 km
Distance rings around the epicentre, with the nearest towns at their true direction. Not a shaking map — see the USGS ShakeMap for that.
When
11:42 am AST on 6 October 2026 ()
Where
7 km (4 mi) NNW of Trujillo Alto, PR · earthquakes near Trujillo Alto
Magnitude
M 3.1 (md)
Depth
113 km below the surface
Felt
no reports yet
Nearest
San Juan Municipio, 3 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2 hours ago

A magnitude 3.1 earthquake was recorded 7 km (4 mi) NNW of Trujillo Alto, PR, at 11:42 am AST on 6 October 2026 (15:42 UTC). This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

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

How big was it?

This earthquake released about 1,200 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 280,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 12,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 8,800× the energy of this one
  4. This earthquake M 3.1 about 1,200 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.3× 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 4.2 on 2026-04-13 — about 43 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 · 19 km SSW of this epicentre
  2. 5.0 3 km N of Brenas, Puerto Rico · 33 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 18.4088, -66.0447. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Juan Municipio, PR 3 km (2 mi) WNW earthquakes near San Juan Municipio
Carolina Municipio, PR 8 km (5 mi) E earthquakes near Carolina Municipio
Trujillo Alto Municipio, PR 9 km (6 mi) SSE earthquakes near Trujillo Alto Municipio
Guaynabo Municipio, PR 10 km (6 mi) SW earthquakes near Guaynabo Municipio
Loíza Municipio, PR 12 km (7 mi) ENE earthquakes near Loíza Municipio
Cataño Municipio, PR 12 km (7 mi) WNW earthquakes near Cataño Municipio

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

Aftershocks so far

No further earthquakes have been recorded within 50 km since this one.

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.