QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near Río Lajas, PR

No earthquake was likely felt in Río Lajas in the 24 hours to 10:10 am AST (14:10 UTC). The last one was M 4.8, 88 km (55 mi) SW, at 9:19 am AST on 18 September 2026, estimated intensity III (weak) in town; 86 felt reports to USGS. Every earthquake near Río Lajas

This page: a magnitude 3.1 earthquake was recorded in Río Lajas, PR, at 5:38 pm AST on 7 December 2019 (21:38 UTC), 112 km deep.

USGS: 0 km ESE of Río Lajas, Puerto Rico

11 km (7 mi) W of Bayamón, PR

5:38 pm AST, Dec 7, 2019 · · 112 km deep · released about 1,300 lb of TNT

Every earthquake near Río Lajas Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Toa Alta Municipio 4 kmDorado Municipio 9 kmVega Alta Municipio 9 kmToa Baja Municipio 10 kmBayamón Municipio 11 kmNaranjito Municipio 12 kmCorozal Municipio 12 kmCataño Municipio 13 kmVega Baja 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
5:38 pm AST on 7 December 2019 ()
Where
in Río Lajas, PR · earthquakes near Río Lajas
Magnitude
M 3.1 (md)
Depth
112 km below the surface
Felt
no reports yet
Nearest
Toa Alta Municipio, 4 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2447 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. 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: San José, Toa Alta, Galateo, Campanilla, Mucarabones, H. Rivera Colon.

How big was it?

This earthquake released about 1,300 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 6.7 260,000× 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 8,200× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× 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 4.4 on 2018-12-09 — about 92 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 · 37 km WNW of this epicentre
  2. 5.1 3 km W of Aguas Buenas, Puerto Rico · 20 km SE of this epicentre
  3. 5.0 3 km N of Brenas, Puerto Rico · 15 km NW 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 18.3930, -66.2633. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Toa Alta Municipio, PR 4 km (2 mi) SSE earthquakes near Toa Alta Municipio
Dorado Municipio, PR 9 km (6 mi) N earthquakes near Dorado Municipio
Vega Alta Municipio, PR 9 km (6 mi) WNW earthquakes near Vega Alta Municipio
Toa Baja Municipio, PR 10 km (6 mi) NE earthquakes near Toa Baja Municipio
Bayamón Municipio, PR 11 km (7 mi) ESE earthquakes near Bayamón Municipio
Naranjito Municipio, PR 12 km (7 mi) S earthquakes near Naranjito 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. 1.7 7 km SW of Jayuya, Puerto Rico
  2. 2.4 5 km N of Jayuya, Puerto Rico
  3. 2.2 6 km N of Yaurel, Puerto Rico
  4. 2.6 25 km N of Dorado, Puerto Rico
  5. 2.0 1 km SW of Las Ochenta, Puerto Rico
  6. 1.5 5 km N of Yaurel, Puerto Rico
  7. 2.4 3 km ENE of Mariano Colón, Puerto Rico
  8. 2.6 7 km NNE of Animas, Puerto Rico
  9. 2.3 1 km NW of Jauca, Puerto Rico
  10. 2.3 2 km SW of Vázquez, Puerto Rico
  11. 2.5 1 km SW of Bairoa, Puerto Rico
  12. 2.0 2 km WSW of Vázquez, 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.