QuakeIndex

Earthquake · reviewed by a seismologist

M 4.4ml

Earthquake near San Juan, PR

No earthquake was likely felt in San Juan in the 24 hours to 4:28 am AST (08:28 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 4.4 earthquake was recorded 47 km (29 mi) northwest of San Juan, PR, at 7:00 pm AST on 9 December 2018 (23:00 UTC), 62 km deep. 39 people have reported feeling it to USGS.

USGS: 36 km N of Brenas, Puerto Rico

55 km (34 mi) NW of San Juan, PR · 52 km (32 mi) NNW of Bayamón, PR

7:00 pm AST, Dec 9, 2018 · · 62 km deep · released about 60 tons of TNT

Every earthquake near San Juan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Vega Baja Municipio 38 kmDorado Municipio 38 kmVega Alta Municipio 40 kmBarceloneta Municipio 41 kmManatí Municipio 41 kmToa Baja Municipio 43 kmCataño Municipio 46 kmToa Alta Municipio 50 kmArecibo Municipio 51 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
7:00 pm AST on 9 December 2018 ()
Where
47 km (29 mi) northwest of San Juan, PR · earthquakes near San Juan
Magnitude
M 4.4 (ml)
Depth
62 km below the surface
Felt
39 reports · strongest reported intensity IV
Nearest
Vega Baja Municipio, 38 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2825 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 114 km (71 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.

Likely felt in: Vega Baja 39 km, intensity III · Dorado 39 km, intensity II · San Antonio 39 km, intensity II · Barceloneta 42 km, intensity II · Levittown 44 km, intensity II · San Juan 47 km, intensity II · Cataño 48 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 60 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,800× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 130× the energy of this one
  3. Magna, Utah 2020 M 5.7 89× the energy of this one
  4. This earthquake M 4.4 about 60 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 130× 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 4.8 on 2017-08-18 — about 4 times the energy of this one.

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

  1. 5.8 12 km N of Garrochales, Puerto Rico · 32 km SW of this epicentre
  2. 5.7 78 km N of Tierras Nuevas Poniente, Puerto Rico · 45 km NNW of this epicentre
  3. 5.5 64 km N of Tierras Nuevas Poniente, Puerto Rico · 29 km NNW of this epicentre
  4. 5.1 66 km N of Brenas, Puerto Rico · 31 km N of this epicentre
  5. 5.0 3 km N of Brenas, Puerto Rico · 33 km S 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 18.7953, -66.3821. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Vega Baja Municipio, PR 38 km (24 mi) S earthquakes near Vega Baja Municipio
Dorado Municipio, PR 38 km (24 mi) SSE earthquakes near Dorado Municipio
Vega Alta Municipio, PR 40 km (25 mi) S earthquakes near Vega Alta Municipio
Barceloneta Municipio, PR 41 km (25 mi) SSW earthquakes near Barceloneta Municipio
Manatí Municipio, PR 41 km (25 mi) SSW earthquakes near Manatí Municipio
Toa Baja Municipio, PR 43 km (26 mi) SSE earthquakes near Toa Baja Municipio

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

Aftershocks so far

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

  1. 2.1 37 km N of San Juan, Puerto Rico
  2. 2.4 13 km N of Carrizales, Puerto Rico
  3. 1.5 18 km NNE of Tierras Nuevas Poniente, Puerto Rico
  4. 2.5 12 km N of Brenas, Puerto Rico
  5. 2.6 32 km N of Garrochales, Puerto Rico
  6. 2.4 34 km N of Arecibo, Puerto Rico
  7. 2.8 71 km N of San Juan, Puerto Rico
  8. 2.6 70 km N of San Juan, Puerto Rico
  9. 2.7 72 km N of San Juan, Puerto Rico
  10. 2.7 73 km N of San Juan, Puerto Rico
  11. 2.8 72 km N of San Juan, Puerto Rico
  12. 1.6 19 km N of Tierras Nuevas Poniente, Puerto Rico
  13. 2.8 1 km SSW of Levittown, Puerto Rico
  14. 2.8 0 km NE of La Luisa, Puerto Rico
  15. 2.5 19 km NNW of Garrochales, 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.