QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

Earthquake near Salinas, PR

No earthquake was likely felt in Salinas in the 24 hours to 4:21 pm AST (20:21 UTC). The last one was M 2.2, 8 km (5 mi) NW, at 5:05 pm AST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Salinas

This page: a magnitude 3.4 earthquake was recorded 4 km (2 mi) east-southeast of Salinas, PR, at 12:49 pm AST on 12 December 2021 (16:49 UTC), 8.0 km deep.

USGS: 3 km ESE of Salinas, Puerto Rico

54 km (33 mi) SSW of San Juan, PR · 38 km (24 mi) SW of Caguas, PR

12:49 pm AST, Dec 12, 2021 · · 8.0 km deep · released about 2 tons of TNT

Every earthquake near Salinas Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Salinas Municipio 1 kmSanta Isabel Municipio 13 kmGuayama Municipio 13 kmCoamo Municipio 19 kmAibonito Municipio 19 kmCayey Municipio 20 kmArroyo Municipio 23 kmJuana Díaz Municipio 24 kmCidra Municipio 26 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
12:49 pm AST on 12 December 2021 ()
Where
4 km (2 mi) east-southeast of Salinas, PR · earthquakes near Salinas
Magnitude
M 3.4 (md)
Depth
8.0 km below the surface
Felt
no reports yet
Nearest
Salinas Municipio, 1 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1721 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 58 km (36 mi) from the epicentre. In Salinas, 4 km away, the estimate is intensity III (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: Santa Isabel 15 km, intensity III · Guayama 16 km, intensity III · Coamo 16 km, intensity III · Cayey 20 km, intensity III · Río Cañas Abajo 23 km, intensity III · Sumidero 32 km, intensity II · Jagual 36 km, intensity II · Caguas 38 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 2 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 86,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 3,800× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,700× the energy of this one
  4. This earthquake M 3.4 about 2 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4.1× 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 5.6 on 2020-01-07 — about 1,900 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.1 3 km W of Aguas Buenas, Puerto Rico · 36 km NNE 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 17.9625, -66.2638. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Salinas Municipio, PR 1 km (1 mi) N earthquakes near Salinas Municipio
Santa Isabel Municipio, PR 13 km (8 mi) W earthquakes near Santa Isabel Municipio
Guayama Municipio, PR 13 km (8 mi) E earthquakes near Guayama Municipio
Coamo Municipio, PR 19 km (12 mi) NNW earthquakes near Coamo Municipio
Aibonito Municipio, PR 19 km (12 mi) N earthquakes near Aibonito Municipio
Cayey Municipio, PR 20 km (12 mi) NE earthquakes near Cayey Municipio

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

Aftershocks so far

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

  1. 2.4 23 km S of Arroyo, Puerto Rico
  2. 2.5 2 km SSE of Tallaboa, Puerto Rico
  3. 3.5 10 km S of Central Aguirre, Puerto Rico
  4. 1.6 2 km SSE of Salinas, Puerto Rico
  5. 3.3 18 km S of Emajagua, Puerto Rico
  6. 3.1 12 km S of Central Aguirre, Puerto Rico
  7. 2.8 10 km S of Central Aguirre, Puerto Rico
  8. 3.2 6 km WNW of Palomas, Puerto Rico
  9. 2.5 3 km NE of Las Ochenta, Puerto Rico
  10. 3.0 3 km N of Tallaboa Alta, Puerto Rico
  11. 2.9 3 km N of Tallaboa Alta, Puerto Rico
  12. 2.5 2 km SSW of Potala Pastillo, Puerto Rico
  13. 2.8 7 km SSE of Tallaboa, Puerto Rico
  14. 2.5 8 km SSE of Tallaboa, Puerto Rico
  15. 2.5 2 km SSW of Salinas, 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.