QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

104 km NW of San Antonio, Puerto Rico

Yes. A magnitude 2.8 earthquake was recorded 104 km NW of San Antonio, Puerto Rico, at 11:08 pm AST on 21 December 2019 (03:08 UTC), 34 km deep.

· 34 km deep · released about 420 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Aguadilla Municipio 103 kmIsabela Municipio 111 kmAguada Municipio 111 kmRincón Municipio 112 kmMoca Municipio 117 kmQuebradillas Municipio 118 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
Magnitude
M 2.8 (md)
Depth
34 km below the surface
Felt
no reports yet
Nearest
Aguadilla Municipio, 103 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2440 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. 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 420 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 36,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 26,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.3× the energy of this one
  4. This earthquake M 2.8 about 420 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 6.0 on 2019-09-24 — about 72,000 times the energy of this one.

Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 94 km NE of Punta Cana, Dominican Republic · 17 km SSW of this epicentre
  2. 6.1 80 km NE of Punta Cana, Dominican Republic · 30 km WSW of this epicentre
  3. 6.0 93 km NNW of San Antonio, Puerto Rico · 39 km E of this epicentre
  4. 6.0 67 km NNW of San Antonio, Puerto Rico · 47 km ESE of this epicentre
  5. 5.7 88 km N of San Antonio, Puerto Rico · 43 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 19.2738, -67.6560. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aguadilla Municipio, PR 103 km (64 mi) SSE earthquakes near Aguadilla Municipio
Isabela Municipio, PR 111 km (69 mi) SE earthquakes near Isabela Municipio
Aguada Municipio, PR 111 km (69 mi) SSE earthquakes near Aguada Municipio
Rincón Municipio, PR 112 km (70 mi) SSE earthquakes near Rincón Municipio
Moca Municipio, PR 117 km (72 mi) SSE earthquakes near Moca Municipio
Quebradillas Municipio, PR 118 km (73 mi) SE earthquakes near Quebradillas Municipio

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

Aftershocks so far

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

  1. 3.4 94 km NE of Punta Cana, Dominican Republic
  2. 3.3 94 km NNW of San Antonio, Puerto Rico
  3. 3.0 98 km NE of Punta Cana, Dominican Republic
  4. 3.0 91 km NE of Punta Cana, Dominican Republic
  5. 3.2 100 km NNW of San Antonio, Puerto Rico
  6. 3.4 100 km NNW of San Antonio, Puerto Rico
  7. 3.2 77 km NNW of San Antonio, Puerto Rico
  8. 2.8 107 km N of San Antonio, Puerto Rico
  9. 2.9 108 km NNW of San Antonio, Puerto Rico
  10. 3.0 92 km NNW of San Antonio, Puerto Rico
  11. 3.0 86 km N of San Antonio, Puerto Rico
  12. 3.5 89 km NNW of San Antonio, Puerto Rico
  13. 3.4 85 km N of San Antonio, Puerto Rico
  14. 4.0 82 km N of San Antonio, Puerto Rico
  15. 2.8 95 km NNW of San Antonio, 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.