QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

93 km N of San Juan, Puerto Rico

Yes. A magnitude 3.4 earthquake was recorded 93 km N of San Juan, Puerto Rico, at 5:02 am AST on 27 August 2023 (09:02 UTC), 90 km deep.

· 90 km deep · released about 2.1 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Dorado Municipio 95 kmToa Baja Municipio 96 kmCataño Municipio 97 kmLoíza Municipio 97 kmSan Juan Municipio 99 kmVega Baja Municipio 101 kmVega Alta Municipio 101 kmCarolina Municipio 102 kmManatí Municipio 106 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 3.4 (md)
Depth
90 km below the surface
Felt
no reports yet
Nearest
Dorado Municipio, 95 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1172 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. 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 2.1 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 80,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 3,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,500× the energy of this one
  4. This earthquake M 3.4 about 2.1 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4.4× 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 4.8 on 2017-08-18 — about 110 times the energy of this one.

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

  1. 5.4 106 km N of Brenas, Puerto Rico · 35 km WNW of this epicentre
  2. 5.1 66 km N of Brenas, Puerto Rico · 41 km SW of this epicentre
  3. 5.1 92 km N of Suárez, Puerto Rico · 37 km E of this epicentre
  4. 5.0 113 km N of Brenas, Puerto Rico · 33 km NW 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 19.3118, -66.0717. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Dorado Municipio, PR 95 km (59 mi) SSW earthquakes near Dorado Municipio
Toa Baja Municipio, PR 96 km (60 mi) S earthquakes near Toa Baja Municipio
Cataño Municipio, PR 97 km (60 mi) S earthquakes near Cataño Municipio
Loíza Municipio, PR 97 km (60 mi) S earthquakes near Loíza Municipio
San Juan Municipio, PR 99 km (61 mi) S earthquakes near San Juan Municipio
Vega Baja Municipio, PR 101 km (63 mi) SSW earthquakes near Vega Baja Municipio

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

Aftershocks so far

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

  1. 3.4 111 km N of San Juan, Puerto Rico
  2. 3.1 61 km N of Brenas, Puerto Rico
  3. 3.3 71 km N of Tierras Nuevas Poniente, Puerto Rico
  4. 3.6 91 km N of Suárez, Puerto Rico
  5. 3.2 89 km N of Brenas, Puerto Rico
  6. 3.7 132 km N of Suárez, Puerto Rico
  7. 3.2 63 km N of San Juan, 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. 3.6 71 km N of Tierras Nuevas Poniente, Puerto Rico
  12. 3.9 98 km N of Brenas, Puerto Rico
  13. 3.9 111 km N of Brenas, Puerto Rico
  14. 3.4 104 km NNE of San Juan, Puerto Rico
  15. 3.8 129 km N of Su?rez, 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.