QuakeIndex

Earthquake · reviewed by a seismologist

M 2.7md

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 4:30 pm AST (20:30 UTC). The last one was M 4.1, 99 km (62 mi) SE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near San Juan

This page: a magnitude 2.7 earthquake was recorded 47 km (29 mi) north of San Juan, PR, at 4:32 pm AST on 8 December 2018 (20:32 UTC), 14 km deep.

USGS: 46 km N of San Juan, Puerto Rico

54 km (34 mi) N of San Juan, PR

4:32 pm AST, Dec 8, 2018 · · 14 km deep · released about 310 lb of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Dorado Municipio 47 kmToa Baja Municipio 48 kmCataño Municipio 49 kmSan Juan Municipio 52 kmVega Alta Municipio 53 kmLoíza Municipio 54 kmVega Baja Municipio 54 kmCarolina Municipio 58 kmToa Alta Municipio 59 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
4:32 pm AST on 8 December 2018 ()
Where
47 km (29 mi) north of San Juan, PR · earthquakes near San Juan
Magnitude
M 2.7 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Dorado Municipio, 47 km SSW
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, people at rest would likely notice it out to about 21 km (13 mi) from the epicentre. In San Juan, 47 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.

How big was it?

This earthquake released about 310 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 50,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 35,000× the energy of this one
  3. Around the size people start to feel M 3.0 3.1× the energy of this one
  4. This earthquake M 2.7 about 310 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

The largest earthquake within 50 km since 2016 was M 4.8 on 2017-08-18 — about 1,600 times the energy of this one.

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

  1. 5.5 64 km N of Tierras Nuevas Poniente, Puerto Rico · 39 km WNW of this epicentre
  2. 5.1 66 km N of Brenas, Puerto Rico · 31 km NW of this epicentre
  3. 5.0 3 km N of Brenas, Puerto Rico · 47 km SSW 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 18.8840, -66.1536. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Dorado Municipio, PR 47 km (29 mi) SSW earthquakes near Dorado Municipio
Toa Baja Municipio, PR 48 km (30 mi) S earthquakes near Toa Baja Municipio
Cataño Municipio, PR 49 km (30 mi) S earthquakes near Cataño Municipio
San Juan Municipio, PR 52 km (32 mi) S earthquakes near San Juan Municipio
Vega Alta Municipio, PR 53 km (33 mi) SSW earthquakes near Vega Alta Municipio
Loíza Municipio, PR 54 km (33 mi) SSE earthquakes near Loíza Municipio

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

Aftershocks so far

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

  1. 2.6 37 km N of Tierras Nuevas Poniente, Puerto Rico
  2. 3.1 69 km N of Tierras Nuevas Poniente, Puerto Rico
  3. 2.5 70 km N of San Juan, Puerto Rico
  4. 1.9 24 km NNE of Tierras Nuevas Poniente, Puerto Rico
  5. 2.5 31 km NNE of San Juan, Puerto Rico
  6. 1.7 50 km N of San Juan, Puerto Rico
  7. 2.7 68 km N of Suárez, Puerto Rico
  8. 2.0 52 km N of Loíza, Puerto Rico
  9. 2.6 68 km N of Suárez, Puerto Rico
  10. 2.4 24 km N of Dorado, Puerto Rico
  11. 2.8 73 km N of Tierras Nuevas Poniente, Puerto Rico
  12. 2.0 20 km NE of San Juan, Puerto Rico
  13. 3.1 37 km NNE of Vieques, Puerto Rico
  14. 2.6 24 km N of San Juan, Puerto Rico
  15. 2.9 13 km NNW of Brenas, 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.