QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9Md

Earthquake near Río Grande, PR

No earthquake was likely felt in Río Grande in the 24 hours to 10:13 am AST (14:13 UTC). The last one was M 4.1, 70 km (44 mi) SE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near Río Grande

This page: a magnitude 2.9 earthquake was recorded 47 km (29 mi) north-northeast of Río Grande, PR, at 2:47 pm AST on 31 March 2017 (18:47 UTC), 56 km deep.

USGS: 42 km NNE of Vieques, Puerto Rico

57 km (35 mi) NE of San Juan, PR · 51 km (32 mi) NE of Carolina, PR

2:47 pm AST, Mar 31, 2017 · · 56 km deep · released about 680 lb of TNT

Every earthquake near Río Grande Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 45 kmFajardo Municipio 46 kmLuquillo Municipio 47 kmRío Grande Municipio 47 kmCarolina Municipio 52 kmCanóvanas Municipio 54 kmSan Juan Municipio 56 kmTrujillo Alto Municipio 59 kmCataño Municipio 60 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
2:47 pm AST on 31 March 2017 ()
Where
47 km (29 mi) north-northeast of Río Grande, PR · earthquakes near Río Grande
Magnitude
M 2.9 (Md)
Depth
56 km below the surface
Felt
no reports yet
Nearest
Loíza Municipio, 45 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3435 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 it was probably too small to be felt, even directly above it. In Río Grande, 47 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.

How big was it?

This earthquake released about 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.4× the energy of this one
  4. This earthquake M 2.9 about 680 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 4.0 on 2016-09-05 — about 45 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.0 73 km NNE of Vieques, Puerto Rico · 32 km NE 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 18.7887, -65.7080. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 45 km (28 mi) SSW earthquakes near Loíza Municipio
Fajardo Municipio, PR 46 km (29 mi) SSE earthquakes near Fajardo Municipio
Luquillo Municipio, PR 47 km (29 mi) S earthquakes near Luquillo Municipio
Río Grande Municipio, PR 47 km (29 mi) SSW earthquakes near Río Grande Municipio
Carolina Municipio, PR 52 km (32 mi) SSW earthquakes near Carolina Municipio
Canóvanas Municipio, PR 54 km (34 mi) SSW earthquakes near Canóvanas Municipio

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

Aftershocks so far

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

  1. 2.6 68 km N of Culebra, Puerto Rico
  2. 2.2 71 km N of Culebra, Puerto Rico
  3. 2.3 53 km N of Culebra, Puerto Rico
  4. 2.9 47 km NNE of San Juan, Puerto Rico
  5. 3.1 82 km NNE of Luquillo, Puerto Rico
  6. 2.1 87 km NNE of Luquillo, Puerto Rico
  7. 3.3 82 km N of Culebra, Puerto Rico
  8. 2.5 17 km N of Loíza, Puerto Rico
  9. 2.5 37 km N of Culebra, Puerto Rico
  10. 2.1 64 km NNE of Luquillo, Puerto Rico
  11. 2.6 27 km NNE of Luquillo, Puerto Rico
  12. 2.9 8 km ENE of San Juan, Puerto Rico
  13. 2.6 83 km NNE of Luquillo, Puerto Rico
  14. 2.4 86 km NNE of Luquillo, Puerto Rico
  15. 2.8 26 km NNE of Luquillo, 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.