QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0md

111 km N of San Juan, Puerto Rico

Yes. A magnitude 4.0 earthquake was recorded 111 km N of San Juan, Puerto Rico, at 6:18 pm AST on 21 November 2023 (22:18 UTC), 29 km deep. 1 person has reported feeling it to USGS.

· 29 km deep · released about 16 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 113 kmToa Baja Municipio 115 kmDorado Municipio 115 kmCataño Municipio 115 kmSan Juan Municipio 116 kmCarolina Municipio 119 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 4.0 (md)
Depth
29 km below the surface
Felt
1 report · strongest reported intensity III
Nearest
Loíza Municipio, 113 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1014 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 94 km (58 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 16 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 10,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 470× the energy of this one
  3. Magna, Utah 2020 M 5.7 330× the energy of this one
  4. This earthquake M 4.0 about 16 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 34× 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 4.4 on 2016-10-23 — about 3.7 times the energy of this one.

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

  1. 5.4 106 km N of Brenas, Puerto Rico · 47 km W of this epicentre
  2. 5.1 92 km N of Suárez, Puerto Rico · 32 km SE of this epicentre
  3. 5.0 113 km N of Brenas, Puerto Rico · 41 km W 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 19.4626, -65.9391. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 113 km (70 mi) S earthquakes near Loíza Municipio
Toa Baja Municipio, PR 115 km (71 mi) SSW earthquakes near Toa Baja Municipio
Dorado Municipio, PR 115 km (71 mi) SSW earthquakes near Dorado Municipio
Cataño Municipio, PR 115 km (72 mi) S earthquakes near Cataño Municipio
San Juan Municipio, PR 116 km (72 mi) S earthquakes near San Juan Municipio
Carolina Municipio, PR 119 km (74 mi) S earthquakes near Carolina 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. 3.4 112 km N of San Juan, Puerto Rico
  2. 3.2 105 km N of San Juan, Puerto Rico
  3. 3.3 88 km N of Brenas, Puerto Rico
  4. 3.6 105 km N of Suárez, Puerto Rico
  5. 3.9 123 km N of Suárez, Puerto Rico
  6. 3.6 123 km N of Suárez, Puerto Rico
  7. 3.4 74 km N of Suárez, Puerto Rico
  8. 2.8 69 km N of San Juan, Puerto Rico
  9. 3.7 97 km N of Brenas, Puerto Rico
  10. 3.6 108 km NNE of San Juan, Puerto Rico
  11. 3.6 119 km N of San Juan, Puerto Rico
  12. 3.8 127 km N of Suárez, Puerto Rico
  13. 3.5 75 km NNE of San Juan, Puerto Rico
  14. 3.6 124 km N of Suárez, Puerto Rico
  15. 3.2 66 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.