QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

Puerto Rico region

Yes. A magnitude 2.1 earthquake was recorded in the Puerto Rico region, at 9:42 pm AST on 12 August 2017 (01:42 UTC), 9.0 km deep.

· 9.0 km deep · released about 38 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Fajardo Municipio 89 kmCulebra Municipio 91 kmLuquillo Municipio 96 kmRío Grande Municipio 100 kmLoíza Municipio 103 kmCeiba Municipio 104 kmCarolina Municipio 109 kmCanóvanas Municipio 109 kmNaguabo Municipio 113 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 2.1 (md)
Depth
9.0 km below the surface
Felt
no reports yet
Nearest
Fajardo Municipio, 89 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3378 days ago

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

At this magnitude and depth, people at rest would likely notice it out to about 14 km (9 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 38 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 390,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 280,000× the energy of this one
  3. Around the size people start to feel M 3.0 25× the energy of this one
  4. This earthquake M 2.1 about 38 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 in our catalogue was M 4.3 on 2016-09-04 — about 2,200 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 19.1416, -65.2976. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Fajardo Municipio, PR 89 km (56 mi) SSW earthquakes near Fajardo Municipio
Culebra Municipio, PR 91 km (56 mi) S earthquakes near Culebra Municipio
Luquillo Municipio, PR 96 km (60 mi) SSW earthquakes near Luquillo Municipio
Río Grande Municipio, PR 100 km (62 mi) SSW earthquakes near Río Grande Municipio
Loíza Municipio, PR 103 km (64 mi) SW earthquakes near Loíza Municipio
Ceiba Municipio, PR 104 km (65 mi) SSW earthquakes near Ceiba Municipio

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

Aftershocks so far

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

  1. 3.1 108 km NNE of Suárez, Puerto Rico
  2. 3.1 81 km N of Culebra, Puerto Rico
  3. 2.5 54 km NNE of Luquillo, Puerto Rico
  4. 3.2 95 km N of Charlotte Amalie, U.S. Virgin Islands
  5. 2.5 77 km NNW of Charlotte Amalie, U.S. Virgin Islands
  6. 2.4 74 km N of Culebra, Puerto Rico
  7. 2.6 128 km NNW of Charlotte Amalie, U.S. Virgin Islands
  8. 3.4 129 km N of Charlotte Amalie, U.S. Virgin Islands
  9. 2.3 77 km N of Culebra, Puerto Rico
  10. 3.4 75 km N of Culebra, Puerto Rico
  11. 2.9 122 km N of Culebra, Puerto Rico
  12. 2.5 77 km NNW of Charlotte Amalie, U.S. Virgin Islands
  13. 2.8 73 km NNW of Charlotte Amalie, U.S. Virgin Islands
  14. 2.8 Puerto Rico region
  15. 3.1 83 km N of Culebra, 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.