QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near Palmarejo, PR

No earthquake was likely felt in Palmarejo in the 24 hours to 11:30 am AST (15:30 UTC). The last one was M 2.1, 6 km (4 mi) SW, at 11:57 pm AST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Palmarejo

This page: a magnitude 1.5 earthquake was recorded 6 km (4 mi) southwest of Palmarejo, PR, at 4:26 pm AST on 4 August 2021 (20:26 UTC), 3.0 km deep.

USGS: 5 km SW of Palmarejo, Puerto Rico

23 km (14 mi) S of Mayagüez, PR · 119 km (74 mi) WSW of San Juan, PR

4:26 pm AST, Aug 4, 2021 · · 3.0 km deep · released about 5.9 lb of TNT

Every earthquake near Palmarejo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cabo Rojo Municipio 8 kmLajas Municipio 8 kmSan Germán Municipio 14 kmHormigueros Municipio 15 kmSabana Grande Municipio 20 kmGuánica Municipio 20 kmMaricao Municipio 27 kmYauco Municipio 28 kmLas Marías Municipio 29 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
4:26 pm AST on 4 August 2021 ()
Where
6 km (4 mi) southwest of Palmarejo, PR · earthquakes near Palmarejo
Magnitude
M 1.5 (md)
Depth
3.0 km below the surface
Felt
no reports yet
Nearest
Cabo Rojo Municipio, 8 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1925 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 10 km (6 mi) from the epicentre. In Palmarejo, 6 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: Pole Ojea 8 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
  3. Around the size people start to feel M 3.0 160× the energy of this one
  4. This earthquake M 1.5 about 5.9 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 6.4 on 2020-01-07 — about 20,000,000 times the energy of this one.

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

  1. 5.8 4 km E of Moca, Puerto Rico · 45 km N of this epicentre
  2. 5.2 19 km SW of Stella, Puerto Rico · 35 km NW of this epicentre
  3. 5.1 21 km SW of Stella, Puerto Rico · 34 km NW 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 17.9978, -67.1093. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cabo Rojo Municipio, PR 8 km (5 mi) W earthquakes near Cabo Rojo Municipio
Lajas Municipio, PR 8 km (5 mi) ESE earthquakes near Lajas Municipio
San Germán Municipio, PR 14 km (9 mi) NNE earthquakes near San Germán Municipio
Hormigueros Municipio, PR 15 km (9 mi) N earthquakes near Hormigueros Municipio
Sabana Grande Municipio, PR 20 km (12 mi) ENE earthquakes near Sabana Grande Municipio
Guánica Municipio, PR 20 km (13 mi) ESE earthquakes near Guánica Municipio

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

Aftershocks so far

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

  1. 3.1 5 km SW of La Parguera, Puerto Rico
  2. 3.4 5 km S of Magas Arriba, Puerto Rico
  3. 3.1 3 km SE of Tallaboa Alta, Puerto Rico
  4. 2.8 8 km SSW of Tallaboa, Puerto Rico
  5. 3.1 7 km WSW of La Parguera, Puerto Rico
  6. 2.5 5 km S of Guánica, Puerto Rico
  7. 3.4 6 km ESE of Pole Ojea, Puerto Rico
  8. 2.6 8 km ESE of Pole Ojea, Puerto Rico
  9. 3.3 7 km SW of La Parguera, Puerto Rico
  10. 3.3 6 km WSW of La Parguera, Puerto Rico
  11. 2.3 Puerto Rico region
  12. 2.3 2 km SE of Maria Antonia, Puerto Rico
  13. 2.0 4 km WSW of La Parguera, Puerto Rico
  14. 2.3 3 km WSW of Guánica, Puerto Rico
  15. 2.5 6 km S of Guánica, 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.