QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

54 km WSW of Stella, Puerto Rico

Yes. A magnitude 3.4 earthquake was recorded 54 km WSW of Stella, Puerto Rico, at 4:24 am AST on 1 January 2021 (08:24 UTC), 51 km deep.

· 51 km deep · released about 1.8 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Mayagüez Municipio 19 kmRincón Municipio 54 kmCabo Rojo Municipio 61 kmAguada Municipio 62 kmAñasco Municipio 65 kmHormigueros Municipio 65 kmAguadilla Municipio 71 kmMoca Municipio 73 kmSan Germán Municipio 74 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 3.4 (md)
Depth
51 km below the surface
Felt
no reports yet
Nearest
Mayagüez Municipio, 19 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2141 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 25 km (16 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 1.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 92,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,100× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,900× the energy of this one
  4. This earthquake M 3.4 about 1.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3.8× 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 4.4 on 2017-10-01 — about 33 times the energy of this one.

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

  1. 6.3 58 km E of Punta Cana, Dominican Republic · 39 km NNW of this epicentre
  2. 5.2 19 km SW of Stella, Puerto Rico · 38 km E of this epicentre
  3. 5.1 21 km SW of Stella, Puerto Rico · 38 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 18.1663, -67.7316. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mayagüez Municipio, PR 19 km (12 mi) WSW earthquakes near Mayagüez Municipio
Rincón Municipio, PR 54 km (34 mi) ENE earthquakes near Rincón Municipio
Cabo Rojo Municipio, PR 61 km (38 mi) ESE earthquakes near Cabo Rojo Municipio
Aguada Municipio, PR 62 km (39 mi) ENE earthquakes near Aguada Municipio
Añasco Municipio, PR 65 km (40 mi) ENE earthquakes near Añasco Municipio
Hormigueros Municipio, PR 65 km (40 mi) E earthquakes near Hormigueros Municipio

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

Aftershocks so far

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

  1. 3.9 Mona Passage
  2. 2.7 7 km SW of Stella, Puerto Rico
  3. 2.4 16 km SSW of Stella, Puerto Rico
  4. 3.5 19 km WNW of Rincón, Puerto Rico
  5. 3.2 5 km SW of Stella, Puerto Rico
  6. 3.1 65 km W of Puerto Real, Puerto Rico
  7. 2.0 9 km W of Puerto Real, Puerto Rico
  8. 3.4 56 km SE of Punta Cana, Dominican Republic
  9. 2.3 17 km SW of Stella, Puerto Rico
  10. 2.5 22 km W of Pole Ojea, Puerto Rico
  11. 2.2 29 km W of Stella, Puerto Rico
  12. 2.5 18 km WNW of Puerto Real, Puerto Rico
  13. 3.0 54 km W of Rincón, Puerto Rico
  14. 3.9 40 km WNW of Rincón, Puerto Rico
  15. 2.9 24 km W of Puerto Real, 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.