QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near Lares, PR

No earthquake was likely felt in Lares in the 24 hours to 5:15 pm AST (21:15 UTC). The last one was M 3.1, 39 km (24 mi) S, at 3:58 pm AST on 31 October 2026, estimated intensity II (weak) in town. Every earthquake near Lares

This page: a magnitude 3.1 earthquake was recorded 9 km (6 mi) south of Lares, PR, at 12:48 pm AST on 12 September 2021 (16:48 UTC), 29 km deep. 1 person has reported feeling it to USGS.

USGS: 9 km S of Lares, Puerto Rico

34 km (21 mi) NW of Ponce, PR · 30 km (18 mi) E of Mayagüez, PR

12:48 pm AST, Sep 12, 2021 · · 29 km deep · released about 1,600 lb of TNT

Every earthquake near Lares Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lares Municipio 7 kmMaricao Municipio 9 kmAdjuntas Municipio 11 kmLas Marías Municipio 12 kmYauco Municipio 14 kmSabana Grande Municipio 17 kmSan Sebastián Municipio 17 kmUtuado Municipio 18 kmSan Germán Municipio 22 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
12:48 pm AST on 12 September 2021 ()
Where
9 km (6 mi) south of Lares, PR · earthquakes near Lares
Magnitude
M 3.1 (md)
Depth
29 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Lares Municipio, 7 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1556 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 33 km (21 mi) from the epicentre. In Lares, 9 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: Lares 9 km, intensity II · Adjuntas 16 km, intensity II · San Sebastián 19 km, intensity II · Yauco 20 km, intensity II · Guayanilla 23 km, intensity II · Magas Arriba 24 km, intensity II · San Germán 24 km, intensity II · Tallaboa Alta 25 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1,600 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 210,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 9,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,700× the energy of this one
  4. This earthquake M 3.1 about 1,600 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.7× 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 75,000 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 6.3 6 km WNW of Aguadilla, Puerto Rico · 45 km NW of this epicentre
  2. 5.8 12 km N of Garrochales, Puerto Rico · 50 km NE of this epicentre
  3. 5.8 4 km E of Moca, Puerto Rico · 30 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 18.2120, -66.8610. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lares Municipio, PR 7 km (5 mi) N earthquakes near Lares Municipio
Maricao Municipio, PR 9 km (6 mi) WSW earthquakes near Maricao Municipio
Adjuntas Municipio, PR 11 km (7 mi) ESE earthquakes near Adjuntas Municipio
Las Marías Municipio, PR 12 km (8 mi) W earthquakes near Las Marías Municipio
Yauco Municipio, PR 14 km (9 mi) S earthquakes near Yauco Municipio
Sabana Grande Municipio, PR 17 km (10 mi) SSW earthquakes near Sabana Grande Municipio

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

Aftershocks so far

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

  1. 1.6 6 km WSW of Fuig, Puerto Rico
  2. 2.1 4 km SSW of Indios, Puerto Rico
  3. 3.0 6 km W of La Parguera, Puerto Rico
  4. 2.5 2 km ENE of Maria Antonia, Puerto Rico
  5. 1.8 5 km WSW of La Parguera, Puerto Rico
  6. 2.5 Puerto Rico region
  7. 2.4 4 km ESE of Indios, Puerto Rico
  8. 2.5 8 km SSE of Maria Antonia, Puerto Rico
  9. 2.6 7 km SSE of Maria Antonia, Puerto Rico
  10. 3.1 7 km ESE of Pole Ojea, Puerto Rico
  11. 2.0 5 km E of La Parguera, Puerto Rico
  12. 2.5 5 km WNW of Fuig, Puerto Rico
  13. 2.3 4 km W of Fuig, Puerto Rico
  14. 2.1 3 km SW of Guánica, Puerto Rico
  15. 2.2 5 km WSW of Guánica, 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.