QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mb

53 km N of Brenas, Puerto Rico

Yes. A magnitude 4.8 earthquake was recorded 53 km N of Brenas, Puerto Rico, 66 km (41 mi) NNW of San Juan, PR, at 4:13 pm AST on 18 August 2017 (20:13 UTC), 42 km deep. 65 people have reported feeling it to USGS.

66 km (41 mi) NNW of San Juan, PR

· 42 km deep · released about 240 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Dorado Municipio 53 kmVega Baja Municipio 55 kmToa Baja Municipio 56 kmVega Alta Municipio 57 kmCataño Municipio 58 kmManatí Municipio 59 kmBarceloneta Municipio 59 kmSan Juan Municipio 64 kmToa Alta Municipio 65 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 4.8 (mb)
Depth
42 km below the surface
Felt
65 reports · strongest reported intensity V
Nearest
Dorado Municipio, 53 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1557 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 165 km (103 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 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 710× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 240 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 500× 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.0 on 2017-03-24.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 78 km N of Arecibo, Puerto Rico · 43 km NW of this epicentre
  2. 5.7 78 km N of Tierras Nuevas Poniente, Puerto Rico · 35 km NW of this epicentre
  3. 5.5 64 km N of Tierras Nuevas Poniente, Puerto Rico · 21 km WNW of this epicentre
  4. 5.1 66 km N of Brenas, Puerto Rico · 15 km NNW of this epicentre
  5. 5.1 68 km N of Hatillo, Puerto Rico · 49 km WNW 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 18.9466, -66.3118. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Dorado Municipio, PR 53 km (33 mi) S earthquakes near Dorado Municipio
Vega Baja Municipio, PR 55 km (34 mi) S earthquakes near Vega Baja Municipio
Toa Baja Municipio, PR 56 km (35 mi) SSE earthquakes near Toa Baja Municipio
Vega Alta Municipio, PR 57 km (35 mi) S earthquakes near Vega Alta Municipio
Cataño Municipio, PR 58 km (36 mi) SSE earthquakes near Cataño Municipio
Manatí Municipio, PR 59 km (37 mi) SSW earthquakes near Manatí Municipio

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

Aftershocks so far

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

  1. 3.2 41 km N of Brenas, Puerto Rico
  2. 2.5 48 km N of Carrizales, Puerto Rico
  3. 2.7 26 km NNW of Brenas, Puerto Rico
  4. 3.2 57 km N of San Juan, Puerto Rico
  5. 2.6 5 km N of Brenas, Puerto Rico
  6. 2.7 72 km N of Tierras Nuevas Poniente, Puerto Rico
  7. 3.0 59 km N of Arecibo, Puerto Rico
  8. 3.0 88 km N of San Juan, Puerto Rico
  9. 2.6 58 km N of Tierras Nuevas Poniente, Puerto Rico
  10. 2.7 10 km NNW of Tierras Nuevas Poniente, Puerto Rico
  11. 2.7 69 km N of Tierras Nuevas Poniente, Puerto Rico
  12. 3.3 4 km NE of Brenas, Puerto Rico
  13. 3.3 12 km NNE of Tierras Nuevas Poniente, Puerto Rico
  14. 3.0 68 km NNE of Arecibo, Puerto Rico
  15. 3.3 74 km N of San Juan, 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.