QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

107 km NNE of Vieques, Puerto Rico

Yes. A magnitude 3.1 earthquake was recorded 107 km NNE of Vieques, Puerto Rico, at 7:44 pm AST on 5 August 2018 (23:44 UTC), 35 km deep.

· 35 km deep · released about 1,200 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Fajardo Municipio 109 kmLoíza Municipio 109 kmLuquillo Municipio 112 kmRío Grande Municipio 112 kmCarolina Municipio 115 kmSan Juan Municipio 117 kmCulebra Municipio 119 kmCataño Municipio 119 kmCanóvanas Municipio 120 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 3.1 (md)
Depth
35 km below the surface
Felt
no reports yet
Nearest
Fajardo Municipio, 109 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2948 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 19 km (12 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 1,200 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 290,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 13,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 9,100× the energy of this one
  4. This earthquake M 3.1 about 1,200 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.2× more

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 4.5 on 2018-03-06 — about 140 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.1 122 km NNE of Vieques, Puerto Rico · 28 km E of this epicentre
  2. 5.1 92 km N of Suárez, Puerto Rico · 20 km SW of this epicentre
  3. 5.0 73 km NNE of Vieques, Puerto Rico · 41 km S 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 19.3628, -65.5716. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Fajardo Municipio, PR 109 km (67 mi) S earthquakes near Fajardo Municipio
Loíza Municipio, PR 109 km (68 mi) SSW earthquakes near Loíza Municipio
Luquillo Municipio, PR 112 km (69 mi) S earthquakes near Luquillo Municipio
Río Grande Municipio, PR 112 km (70 mi) SSW earthquakes near Río Grande Municipio
Carolina Municipio, PR 115 km (72 mi) SSW earthquakes near Carolina Municipio
San Juan Municipio, PR 117 km (73 mi) SSW earthquakes near San Juan Municipio

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

Aftershocks so far

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

  1. 3.1 116 km NNE of Vieques, Puerto Rico
  2. 3.1 108 km NNW of Charlotte Amalie, U.S. Virgin Islands
  3. 3.4 128 km NNE of Vieques, Puerto Rico
  4. 2.5 110 km NNW of Charlotte Amalie, U.S. Virgin Islands
  5. 3.2 125 km N of Culebra, Puerto Rico
  6. 3.4 135 km NNE of Suárez, Puerto Rico
  7. 2.9 127 km NNE of Vieques, Puerto Rico
  8. 3.2 103 km N of San Juan, Puerto Rico
  9. 3.1 Puerto Rico region
  10. 3.6 119 km NNW of Charlotte Amalie, U.S. Virgin Islands
  11. 2.3 77 km NNE of San Juan, Puerto Rico
  12. 2.6 72 km N of Suárez, Puerto Rico
  13. 2.8 93 km N of Culebra, Puerto Rico
  14. 3.1 93 km NNE of San Juan, Puerto Rico
  15. 3.0 85 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.