QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6md

Earthquake near Mayagüez, PR

No earthquake was likely felt in Mayagüez in the 24 hours to 5:41 am AST (09:41 UTC). The last one was M 2.9, 25 km (15 mi) SSE, at 3:17 am AST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Mayagüez

This page: a magnitude 3.6 earthquake was recorded 29 km (18 mi) south of Mayagüez, PR, at 4:42 pm AST on 24 June 2021 (20:42 UTC), 11 km deep. 7 people have reported feeling it to USGS.

USGS: Puerto Rico region

29 km (18 mi) S of Mayagüez, PR · 120 km (75 mi) WSW of San Juan, PR

4:42 pm AST, Jun 24, 2021 · · 11 km deep · released about 3.4 tons of TNT

Every earthquake near Mayagüez Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lajas Municipio 7 kmCabo Rojo Municipio 11 kmGuánica Municipio 18 kmSan Germán Municipio 19 kmHormigueros Municipio 21 kmSabana Grande Municipio 22 kmYauco Municipio 30 kmMaricao Municipio 31 kmGuayanilla Municipio 32 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
4:42 pm AST on 24 June 2021 ()
Where
29 km (18 mi) south of Mayagüez, PR · earthquakes near Mayagüez
Magnitude
M 3.6 (md)
Depth
11 km below the surface
Felt
7 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Lajas Municipio, 7 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1903 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 67 km (42 mi) from the epicentre. In Mayagüez, 29 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 10 km, intensity III · San Germán 16 km, intensity III · Puerto Real 17 km, intensity III · Yauco 28 km, intensity II · Mayagüez 29 km, intensity II · Guayanilla 33 km, intensity II · Magas Arriba 35 km, intensity II · Tallaboa 41 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 3.4 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 50,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,200× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,600× the energy of this one
  4. This earthquake M 3.6 about 3.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.2× 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 in our catalogue was M 6.4 on 2020-01-07 — about 18,000 times the energy of this one.

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 17.9456, -67.0958. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lajas Municipio, PR 7 km (4 mi) ENE earthquakes near Lajas Municipio
Cabo Rojo Municipio, PR 11 km (7 mi) WNW earthquakes near Cabo Rojo Municipio
Guánica Municipio, PR 18 km (11 mi) E earthquakes near Guánica Municipio
San Germán Municipio, PR 19 km (12 mi) NNE earthquakes near San Germán Municipio
Hormigueros Municipio, PR 21 km (13 mi) N earthquakes near Hormigueros Municipio
Sabana Grande Municipio, PR 22 km (14 mi) NE earthquakes near Sabana Grande 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. 2.7 8 km SW of La Parguera, Puerto Rico
  2. 2.2 7 km WSW of La Parguera, Puerto Rico
  3. 2.7 6 km WSW of La Parguera, Puerto Rico
  4. 2.7 5 km WSW of La Parguera, Puerto Rico
  5. 2.1 6 km SSW of La Parguera, Puerto Rico
  6. 2.7 7 km E of La Parguera, Puerto Rico
  7. 2.6 7 km WSW of La Parguera, Puerto Rico
  8. 3.1 7 km WSW of La Parguera, Puerto Rico
  9. 2.6 1 km ESE of Magas Arriba, Puerto Rico
  10. 2.8 7 km SW of Guánica, Puerto Rico
  11. 2.2 4 km SSW of Liborio Negron Torres, Puerto Rico
  12. 2.9 2 km ESE of Magas Arriba, Puerto Rico
  13. 2.8 6 km WSW of La Parguera, Puerto Rico
  14. 2.4 6 km SW of La Parguera, Puerto Rico
  15. 2.9 7 km SW of La Parguera, 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.