QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8md

118 km NNE of Vieques, Puerto Rico

Yes. A magnitude 3.8 earthquake was recorded 118 km NNE of Vieques, Puerto Rico, at 7:36 am AST on 11 August 2023 (11:36 UTC), 11 km deep. 1 person has reported feeling it to USGS.

· 11 km deep · released about 7.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Fajardo Municipio 118 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 3.8 (md)
Depth
11 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Fajardo Municipio, 118 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1121 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 81 km (50 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 7.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 23,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 730× the energy of this one
  4. This earthquake M 3.8 about 7.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 15× 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 4.9 on 2018-11-14 — about 46 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 5.1 122 km NNE of Vieques, Puerto Rico · 16 km E of this epicentre
  2. 5.1 92 km N of Suárez, Puerto Rico · 33 km SW of this epicentre
  3. 5.0 109 km N of Charlotte Amalie, U.S. Virgin Islands · 49 km ESE of this epicentre
  4. 5.0 73 km NNE of Vieques, Puerto Rico · 49 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 19.4381, -65.4675. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Fajardo Municipio, PR 118 km (73 mi) S earthquakes near Fajardo Municipio
Loíza Municipio, PR 121 km (75 mi) SSW earthquakes near Loíza Municipio
Luquillo Municipio, PR 122 km (76 mi) SSW earthquakes near Luquillo Municipio
Río Grande Municipio, PR 123 km (76 mi) SSW earthquakes near Río Grande Municipio
Carolina Municipio, PR 127 km (79 mi) SSW earthquakes near Carolina Municipio
San Juan Municipio, PR 129 km (80 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

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

  1. 3.4 82 km N of Culebra, Puerto Rico
  2. 3.3 92 km N of Culebra, Puerto Rico
  3. 3.7 92 km NNE of Luquillo, Puerto Rico
  4. 3.2 77 km NNE of Vieques, Puerto Rico
  5. 3.9 148 km NNE of Suárez, Puerto Rico
  6. 3.6 91 km N of Suárez, Puerto Rico
  7. 3.7 132 km N of Suárez, Puerto Rico
  8. 3.7 131 km NNE of San Juan, Puerto Rico
  9. 3.3 89 km N of Suárez, Puerto Rico
  10. 3.9 123 km N of Suárez, Puerto Rico
  11. 3.4 104 km NNE of San Juan, Puerto Rico
  12. 3.8 129 km N of Su?rez, Puerto Rico
  13. 3.1 Puerto Rico region
  14. 3.7 93 km N of Culebra, Puerto Rico
  15. 3.6 132 km N of Suárez, 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.