QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

Earthquake near Las Marias, PR

No earthquake was likely felt in Las Marias in the 24 hours to 4:24 pm AST (20:24 UTC). The last one was M 3.5, 12 km (8 mi) NNE, at 12:03 am AST on 6 November 2026, estimated intensity II (weak) in town. Every earthquake near Las Marias

This page: a magnitude 2.1 earthquake was recorded 21 km (13 mi) east-southeast of Las Marias, PR, at 5:05 pm AST on 8 December 2017 (21:05 UTC), 26 km deep.

USGS: 4 km ESE of Las Marías, Puerto Rico

96 km (60 mi) WSW of San Juan, PR · 20 km (12 mi) E of Mayagüez, PR

5:05 pm AST, Dec 8, 2017 · · 26 km deep · released about 40 lb of TNT

Every earthquake near Las Marias Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Las Marías Municipio 2 kmMaricao Municipio 7 kmLares Municipio 10 kmSan Sebastián Municipio 11 kmSan Germán Municipio 16 kmSabana Grande Municipio 16 kmYauco Municipio 19 kmAñasco Municipio 19 kmHormigueros 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
5:05 pm AST on 8 December 2017 ()
Where
21 km (13 mi) east-southeast of Las Marias, PR · earthquakes near Las Marias
Magnitude
M 2.1 (md)
Depth
26 km below the surface
Felt
no reports yet
Nearest
Las Marías Municipio, 2 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3260 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Las Marias, 21 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: Maricao, Juncal, Lares, San Sebastián, Sabana Grande, Espino.

How big was it?

This earthquake released about 40 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 380,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 270,000× the energy of this one
  3. Around the size people start to feel M 3.0 24× the energy of this one
  4. This earthquake M 2.1 about 40 lb of TNT

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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 6.3 6 km WNW of Aguadilla, Puerto Rico · 36 km NW of this epicentre
  2. 6.1 15 km WNW of San Antonio, Puerto Rico · 46 km NW of this epicentre
  3. 5.8 4 km E of Moca, Puerto Rico · 22 km NNW of this epicentre
  4. 5.2 19 km SW of Stella, Puerto Rico · 44 km W of this epicentre
  5. 5.1 21 km SW of Stella, Puerto Rico · 44 km W 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 18.2316, -66.9566. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Las Marías Municipio, PR 2 km (1 mi) WSW earthquakes near Las Marías Municipio
Maricao Municipio, PR 7 km (4 mi) SSE earthquakes near Maricao Municipio
Lares Municipio, PR 10 km (7 mi) ENE earthquakes near Lares Municipio
San Sebastián Municipio, PR 11 km (7 mi) N earthquakes near San Sebastián Municipio
San Germán Municipio, PR 16 km (10 mi) SSW earthquakes near San Germán Municipio
Sabana Grande Municipio, PR 16 km (10 mi) S earthquakes near Sabana Grande Municipio

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

Aftershocks so far

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

  1. 2.8 7 km SSE of Maria Antonia, Puerto Rico
  2. 2.7 13 km WNW of Puerto Real, Puerto Rico
  3. 2.5 18 km SSW of Stella, Puerto Rico
  4. 2.0 12 km WNW of Puerto Real, Puerto Rico
  5. 2.5 Mona Passage
  6. 2.3 18 km WNW of Puerto Real, Puerto Rico
  7. 3.0 11 km N of Camuy, Puerto Rico
  8. 2.0 7 km WSW of Puerto Real, Puerto Rico
  9. 1.7 13 km S of Indios, Puerto Rico
  10. 2.9 6 km NNW of Camuy, Puerto Rico
  11. 2.7 7 km W of Mayagüez, Puerto Rico
  12. 2.5 0 km NNE of Mayagüez, Puerto Rico
  13. 2.0 5 km SE of Ponce, Puerto Rico
  14. 2.2 6 km ENE of La Parguera, Puerto Rico
  15. 1.9 6 km W of Stella, 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.