QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8Md

55 km S of Central Aguirre, Puerto Rico

Yes. A magnitude 2.8 earthquake was recorded 55 km S of Central Aguirre, Puerto Rico, at 11:35 am AST on 21 March 2017 (15:35 UTC), 22 km deep.

· 22 km deep · released about 480 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Salinas Municipio 58 kmGuayama Municipio 58 kmSanta Isabel Municipio 58 kmArroyo Municipio 60 kmPatillas Municipio 65 kmJuana Díaz Municipio 67 kmMaunabo Municipio 69 kmCayey Municipio 73 kmPonce Municipio 74 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
Magnitude
M 2.8 (Md)
Depth
22 km below the surface
Felt
no reports yet
Nearest
Salinas Municipio, 58 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3439 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 17 km (11 mi) from the epicentre. 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.

How big was it?

This earthquake released about 480 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 32,000× 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 2× the energy of this one
  4. This earthquake M 2.8 about 480 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

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 17.4540, -66.2137. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Salinas Municipio, PR 58 km (36 mi) N earthquakes near Salinas Municipio
Guayama Municipio, PR 58 km (36 mi) N earthquakes near Guayama Municipio
Santa Isabel Municipio, PR 58 km (36 mi) NNW earthquakes near Santa Isabel Municipio
Arroyo Municipio, PR 60 km (38 mi) NNE earthquakes near Arroyo Municipio
Patillas Municipio, PR 65 km (41 mi) NNE earthquakes near Patillas Municipio
Juana Díaz Municipio, PR 67 km (42 mi) NNW earthquakes near Juana Díaz Municipio

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

Aftershocks so far

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

  1. 2.0 9 km SSW of Central Aguirre, Puerto Rico
  2. 2.2 9 km SSE of Jobos, Puerto Rico
  3. 2.4 14 km SSE of Central Aguirre, Puerto Rico
  4. 2.7 10 km S of Jobos, Puerto Rico
  5. 2.9 84 km S of Jobos, Puerto Rico
  6. 1.5 10 km S of Jobos, Puerto Rico
  7. 2.8 18 km SSE of Arroyo, Puerto Rico
  8. 1.6 20 km S of Arroyo, Puerto Rico
  9. 2.7 11 km S of Jauca, Puerto Rico
  10. 3.1 12 km S of Santa Isabel, Puerto Rico
  11. 3.0 94 km S of Central Aguirre, Puerto Rico
  12. 2.4 37 km S of Santa Isabel, Puerto Rico
  13. 2.8 21 km SSE of Arroyo, Puerto Rico
  14. 2.4 22 km SSE of Arroyo, Puerto Rico
  15. 2.8 43 km SSW of Potala Pastillo, 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.