QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6md

Earthquake near Guánica, PR

No earthquake was likely felt in Guánica in the 24 hours to 10:50 am AST (14:50 UTC). The last one was M 2.1, 13 km (8 mi) ENE, at 4:39 pm AST on 9 November 2026, estimated intensity II (weak) in town. Every earthquake near Guánica

This page: a magnitude 3.6 earthquake was recorded 4 km (2 mi) west-southwest of Guánica, PR, at 6:59 pm AST on 27 August 2023 (22:59 UTC), 8.0 km deep. 3 people have reported feeling it to USGS.

USGS: 3 km WSW of Guánica, Puerto Rico

34 km (21 mi) W of Ponce, PR · 34 km (21 mi) SE of Mayagüez, PR

6:59 pm AST, Aug 27, 2023 · · 8.0 km deep · released about 3.5 tons of TNT

Every earthquake near Guánica Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Guánica Municipio 3 kmLajas Municipio 10 kmSabana Grande Municipio 13 kmGuayanilla Municipio 16 kmYauco Municipio 16 kmSan Germán Municipio 19 kmMaricao Municipio 23 kmPeñuelas Municipio 24 kmCabo Rojo Municipio 25 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
6:59 pm AST on 27 August 2023 ()
Where
4 km (2 mi) west-southwest of Guánica, PR · earthquakes near Guánica
Magnitude
M 3.6 (md)
Depth
8.0 km below the surface
Felt
3 reports · strongest reported intensity III
Nearest
Guánica Municipio, 3 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1103 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 68 km (42 mi) from the epicentre. In Guánica, 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: Yauco 13 km, intensity III · San Germán 17 km, intensity III · Guayanilla 17 km, intensity III · Magas Arriba 19 km, intensity III · Tallaboa 24 km, intensity III · Pole Ojea 26 km, intensity III · Tallaboa Alta 28 km, intensity III · Puerto Real 29 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 3.5 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 48,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,100× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,500× the energy of this one
  4. This earthquake M 3.6 about 3.5 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.4× 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 6.4 on 2020-01-07 — about 17,000 times the energy of this one.

Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.

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 17.9638, -66.9440. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Guánica Municipio, PR 3 km (2 mi) SE earthquakes near Guánica Municipio
Lajas Municipio, PR 10 km (6 mi) W earthquakes near Lajas Municipio
Sabana Grande Municipio, PR 13 km (8 mi) N earthquakes near Sabana Grande Municipio
Guayanilla Municipio, PR 16 km (10 mi) ENE earthquakes near Guayanilla Municipio
Yauco Municipio, PR 16 km (10 mi) NE earthquakes near Yauco Municipio
San Germán Municipio, PR 19 km (12 mi) NNW earthquakes near San Germán Municipio

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

Aftershocks so far

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

  1. 2.9 Puerto Rico region
  2. 2.3 2 km SW of Guánica, Puerto Rico
  3. 2.3 Puerto Rico region
  4. 2.6 1 km E of Magas Arriba, Puerto Rico
  5. 2.2 1 km SW of Gu?nica, Puerto Rico
  6. 2.7 5 km WSW of Liborio Negron Torres, Puerto Rico
  7. 2.4 Puerto Rico region
  8. 2.4 Puerto Rico region
  9. 2.4 Puerto Rico region
  10. 2.3 Puerto Rico region
  11. 2.3 Puerto Rico region
  12. 2.3 Puerto Rico region
  13. 2.8 Puerto Rico region
  14. 2.5 3 km SW of Guánica, Puerto Rico
  15. 2.3 2 km E of Sabana Grande, 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.