QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

Earthquake near Martorell, PR

No earthquake was likely felt in Martorell in the 24 hours to 12:59 pm AST (16:59 UTC). The last one was M 2.2, 14 km (9 mi) SE, at 2:59 pm AST on 4 November 2026, estimated intensity II (weak) in town. Every earthquake near Martorell

This page: a magnitude 2.8 earthquake was recorded 7 km (4 mi) north of Martorell, PR, at 11:14 pm AST on 20 May 2021 (03:14 UTC), 6.0 km deep. 2 people have reported feeling it to USGS.

USGS: 6 km N of Martorell, Puerto Rico

34 km (21 mi) SSE of San Juan, PR · 17 km (11 mi) SE of Caguas, PR

11:14 pm AST, May 20, 2021 · · 6.0 km deep · released about 490 lb of TNT

Every earthquake near Martorell Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Las Piedras Municipio 7 kmSan Lorenzo Municipio 7 kmJuncos Municipio 10 kmYabucoa Municipio 10 kmHumacao Municipio 13 kmMaunabo Municipio 15 kmGurabo Municipio 17 kmCaguas Municipio 17 kmPatillas Municipio 17 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
11:14 pm AST on 20 May 2021 ()
Where
7 km (4 mi) north of Martorell, PR · earthquakes near Martorell
Magnitude
M 2.8 (md)
Depth
6.0 km below the surface
Felt
2 reports · strongest reported intensity III
Nearest
Las Piedras Municipio, 7 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1556 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 27 km (17 mi) from the epicentre. In Martorell, 7 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: Humacao 9 km, intensity III · Jagual 9 km, intensity III · Emajagua 15 km, intensity II · Caguas 18 km, intensity II · Sumidero 25 km, intensity II · Trujillo Alto 26 km, intensity II · Cayey 27 km, intensity II · Guayama 27 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 490 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 31,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 22,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.9× the energy of this one
  4. This earthquake M 2.8 about 490 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 480 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 · 27 km WNW 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 18.1366, -65.9106. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Las Piedras Municipio, PR 7 km (4 mi) NE earthquakes near Las Piedras Municipio
San Lorenzo Municipio, PR 7 km (4 mi) W earthquakes near San Lorenzo Municipio
Juncos Municipio, PR 10 km (6 mi) N earthquakes near Juncos Municipio
Yabucoa Municipio, PR 10 km (6 mi) SSE earthquakes near Yabucoa Municipio
Humacao Municipio, PR 13 km (8 mi) E earthquakes near Humacao Municipio
Maunabo Municipio, PR 15 km (9 mi) S earthquakes near Maunabo Municipio

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

Aftershocks so far

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

  1. 3.3 18 km S of Emajagua, Puerto Rico
  2. 3.1 12 km S of Central Aguirre, Puerto Rico
  3. 2.8 10 km S of Central Aguirre, Puerto Rico
  4. 3.2 6 km WNW of Palomas, Puerto Rico
  5. 2.5 3 km NE of Las Ochenta, Puerto Rico
  6. 3.1 24 km SE of El Negro, Puerto Rico
  7. 3.6 21 km ESE of Emajagua, Puerto Rico
  8. 2.5 2 km SSW of Salinas, Puerto Rico
  9. 3.6 2 km ESE of Pájaros, Puerto Rico
  10. 3.1 3 km ESE of Salinas, Puerto Rico
  11. 3.4 4 km ESE of Salinas, Puerto Rico
  12. 3.4 3 km ESE of Salinas, Puerto Rico
  13. 3.3 1 km SW of Cayey, Puerto Rico
  14. 2.8 1 km SSW of Cayey, Puerto Rico
  15. 3.0 2 km SW of Canovanas, 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.