QuakeIndex

Earthquake · reviewed by a seismologist

M 2.7md

Earthquake near Garrochales, PR

No earthquake was likely felt in Garrochales in the 24 hours to 1:37 am AST (05:37 UTC). The last one was M 2.9, 12 km (7 mi) NW, at 2:05 am AST on 13 October 2026, estimated intensity II (weak) in town. Every earthquake near Garrochales

This page: a magnitude 2.7 earthquake was recorded 6 km (4 mi) north-northwest of Garrochales, PR, at 3:20 am AST on 8 December 2018 (07:20 UTC), 111 km deep.

USGS: 6 km NNW of Garrochales, Puerto Rico

56 km (35 mi) WNW of San Juan, PR · 17 km (11 mi) ENE of Arecibo, PR

3:20 am AST, Dec 8, 2018 · · 111 km deep · released about 350 lb of TNT

Every earthquake near Garrochales Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Barceloneta Municipio 5 kmManatí Municipio 11 kmArecibo Municipio 13 kmFlorida Municipio 16 kmVega Baja Municipio 20 kmHatillo Municipio 24 kmCiales Municipio 25 kmVega Alta Municipio 27 kmMorovis Municipio 27 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
3:20 am AST on 8 December 2018 ()
Where
6 km (4 mi) north-northwest of Garrochales, PR · earthquakes near Garrochales
Magnitude
M 2.7 (md)
Depth
111 km below the surface
Felt
no reports yet
Nearest
Barceloneta Municipio, 5 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2825 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 Garrochales, 6 km away, the estimate is intensity I (not felt). 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: Barceloneta, Imbery, Sabana Hoyos, Animas, La Luisa, Bufalo.

How big was it?

This earthquake released about 350 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 43,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 31,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.7× the energy of this one
  4. This earthquake M 2.7 about 350 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 2 earthquakes of M5 or more within 50 km:

  1. 5.8 12 km N of Garrochales, Puerto Rico · 6 km NNE of this epicentre
  2. 5.0 3 km N of Brenas, Puerto Rico · 25 km E 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 18.5080, -66.5793. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Barceloneta Municipio, PR 5 km (3 mi) SSE earthquakes near Barceloneta Municipio
Manatí Municipio, PR 11 km (7 mi) SE earthquakes near Manatí Municipio
Arecibo Municipio, PR 13 km (8 mi) SW earthquakes near Arecibo Municipio
Florida Municipio, PR 16 km (10 mi) S earthquakes near Florida Municipio
Vega Baja Municipio, PR 20 km (12 mi) ESE earthquakes near Vega Baja Municipio
Hatillo Municipio, PR 24 km (15 mi) WSW earthquakes near Hatillo Municipio

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

Aftershocks so far

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

  1. 1.6 3 km NNW of Isabela, Puerto Rico
  2. 2.9 11 km NNE of Brenas, Puerto Rico
  3. 1.8 6 km SW of Utuado, Puerto Rico
  4. 2.4 2 km NNE of Tierras Nuevas Poniente, Puerto Rico
  5. 1.9 7 km NE of Utuado, Puerto Rico
  6. 2.1 Puerto Rico region
  7. 2.0 3 km N of Juncal, Puerto Rico
  8. 2.6 0 km ENE of Sabana Seca, Puerto Rico
  9. 1.8 7 km W of Orocovis, Puerto Rico
  10. 2.6 Puerto Rico region
  11. 2.3 10 km NNW of Arecibo, Puerto Rico
  12. 2.1 17 km N of Tierras Nuevas Poniente, Puerto Rico
  13. 1.7 31 km N of Carrizales, Puerto Rico
  14. 2.5 44 km N of Brenas, Puerto Rico
  15. 2.4 30 km N of Hatillo, 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.