QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Palo Seco, PR

No earthquake was likely felt in Palo Seco in the 24 hours to 4:33 pm AST (20:33 UTC). The last one was M 2.2, 13 km (8 mi) ESE, at 2:59 pm AST on 4 November 2026, estimated intensity II (weak) in town. Every earthquake near Palo Seco

This page: a magnitude 1.8 earthquake was recorded 8 km (5 mi) south of Palo Seco, PR, at 9:41 pm AST on 22 April 2021 (01:41 UTC), 14 km deep.

USGS: 8 km S of Palo Seco, Puerto Rico

54 km (34 mi) SSE of San Juan, PR · 35 km (22 mi) SSE of Caguas, PR

9:41 pm AST, Apr 22, 2021 · · 14 km deep · released about 14 lb of TNT

Every earthquake near Palo Seco Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Maunabo Municipio 8 kmPatillas Municipio 10 kmArroyo Municipio 13 kmYabucoa Municipio 16 kmGuayama Municipio 23 kmSan Lorenzo Municipio 24 kmHumacao Municipio 27 kmLas Piedras Municipio 29 kmCayey Municipio 31 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
9:41 pm AST on 22 April 2021 ()
Where
8 km (5 mi) south of Palo Seco, PR · earthquakes near Palo Seco
Magnitude
M 1.8 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Maunabo Municipio, 8 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2029 days ago

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

At this magnitude and depth it was probably too small to be felt, even directly above it. In Palo Seco, 8 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.

Earthquakes near other towns within 30 km: Lamboglia, Maunabo, Emajagua, Palmas, Playita, Patillas.

How big was it?

This earthquake released about 14 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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 4.6 on 2016-12-05 — about 18,000 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 · 43 km NNW 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 17.9338, -65.9246. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Maunabo Municipio, PR 8 km (5 mi) NNE earthquakes near Maunabo Municipio
Patillas Municipio, PR 10 km (6 mi) NW earthquakes near Patillas Municipio
Arroyo Municipio, PR 13 km (8 mi) WNW earthquakes near Arroyo Municipio
Yabucoa Municipio, PR 16 km (10 mi) NNE earthquakes near Yabucoa Municipio
Guayama Municipio, PR 23 km (14 mi) W earthquakes near Guayama Municipio
San Lorenzo Municipio, PR 24 km (15 mi) NNW earthquakes near San Lorenzo Municipio

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

Aftershocks so far

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

  1. 2.4 23 km S of Arroyo, Puerto Rico
  2. 3.6 0 km W of Canovanas, 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. 2.5 3 km NE of Las Ochenta, Puerto Rico
  9. 3.1 24 km SE of El Negro, Puerto Rico
  10. 3.6 21 km ESE of Emajagua, Puerto Rico
  11. 2.5 2 km SSW of Salinas, Puerto Rico
  12. 3.1 3 km ESE of Salinas, Puerto Rico
  13. 3.4 4 km ESE of Salinas, Puerto Rico
  14. 3.4 3 km ESE of Salinas, Puerto Rico
  15. 3.3 1 km SW of Cayey, 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.