QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

113 km N of Hatillo, Puerto Rico

Yes. A magnitude 3.1 earthquake was recorded 113 km N of Hatillo, Puerto Rico, at 11:14 pm AST on 21 December 2019 (03:14 UTC), 16 km deep.

· 16 km deep · released about 1,300 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Isabela Municipio 117 kmQuebradillas Municipio 117 kmBarceloneta Municipio 118 kmCamuy Municipio 119 kmHatillo Municipio 119 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 3.1 (md)
Depth
16 km below the surface
Felt
no reports yet
Nearest
Isabela Municipio, 117 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2516 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 38 km (24 mi) from the epicentre. 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 260,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 12,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 8,200× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× 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 4.7 on 2017-07-17 — about 230 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 81 km N of Isabela, Puerto Rico · 36 km SSW of this epicentre
  2. 5.9 78 km N of Arecibo, Puerto Rico · 39 km SSE of this epicentre
  3. 5.7 78 km N of Tierras Nuevas Poniente, Puerto Rico · 44 km SSE of this epicentre
  4. 5.4 106 km N of Brenas, Puerto Rico · 41 km ESE of this epicentre
  5. 5.1 68 km N of Hatillo, Puerto Rico · 46 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 19.5116, -66.7648. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Isabela Municipio, PR 117 km (73 mi) SSW earthquakes near Isabela Municipio
Quebradillas Municipio, PR 117 km (73 mi) S earthquakes near Quebradillas Municipio
Barceloneta Municipio, PR 118 km (73 mi) S earthquakes near Barceloneta Municipio
Camuy Municipio, PR 119 km (74 mi) S earthquakes near Camuy Municipio
Hatillo Municipio, PR 119 km (74 mi) S earthquakes near Hatillo Municipio
Arecibo Municipio, PR 120 km (75 mi) S earthquakes near Arecibo Municipio

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

Aftershocks so far

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

  1. 3.3 79 km N of Isabela, Puerto Rico
  2. 2.4 83 km N of Isabela, Puerto Rico
  3. 3.1 122 km N of Isabela, Puerto Rico
  4. 2.9 104 km N of Isabela, Puerto Rico
  5. 3.0 94 km N of San Antonio, Puerto Rico
  6. 2.5 93 km N of Isabela, Puerto Rico
  7. 2.6 96 km N of Isabela, Puerto Rico
  8. 2.9 93 km N of Isabela, Puerto Rico
  9. 2.6 92 km N of Isabela, Puerto Rico
  10. 2.7 92 km N of San Antonio, Puerto Rico
  11. 3.0 86 km N of Isabela, Puerto Rico
  12. 2.2 90 km N of Isabela, Puerto Rico
  13. 3.0 84 km N of Isabela, Puerto Rico
  14. 2.8 86 km N of Tierras Nuevas Poniente, Puerto Rico
  15. 2.7 98 km N of Isabela, 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.