QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

74 km N of San Juan, Puerto Rico

Yes. A magnitude 3.1 earthquake was recorded 74 km N of San Juan, Puerto Rico, 81 km (51 mi) N of San Juan, PR, at 4:33 am AST on 1 April 2019 (08:33 UTC), 9.0 km deep.

81 km (51 mi) N of San Juan, PR

· 9.0 km deep · released about 1,600 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 77 kmToa Baja Municipio 78 kmCataño Municipio 78 kmDorado Municipio 79 kmSan Juan Municipio 80 kmCarolina Municipio 82 kmVega Alta Municipio 86 kmRío Grande Municipio 87 kmVega Baja Municipio 87 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
9.0 km below the surface
Felt
no reports yet
Nearest
Loíza Municipio, 77 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2713 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 43 km (27 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 1,600 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 210,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 9,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,700× the energy of this one
  4. This earthquake M 3.1 about 1,600 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.7× 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 300 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.1 66 km N of Brenas, Puerto Rico · 40 km W of this epicentre
  2. 5.1 92 km N of Suárez, Puerto Rico · 31 km ENE 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 19.1341, -65.9890. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 77 km (48 mi) S earthquakes near Loíza Municipio
Toa Baja Municipio, PR 78 km (49 mi) SSW earthquakes near Toa Baja Municipio
Cataño Municipio, PR 78 km (49 mi) SSW earthquakes near Cataño Municipio
Dorado Municipio, PR 79 km (49 mi) SSW earthquakes near Dorado Municipio
San Juan Municipio, PR 80 km (49 mi) S earthquakes near San Juan Municipio
Carolina Municipio, PR 82 km (51 mi) S earthquakes near Carolina Municipio

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

Aftershocks so far

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

  1. 2.5 63 km N of San Juan, Puerto Rico
  2. 2.2 91 km N of Brenas, Puerto Rico
  3. 1.8 68 km N of Tierras Nuevas Poniente, Puerto Rico
  4. 2.1 67 km N of Brenas, Puerto Rico
  5. 3.1 119 km N of San Juan, Puerto Rico
  6. 2.7 69 km N of Brenas, Puerto Rico
  7. 1.9 49 km N of Brenas, Puerto Rico
  8. 2.5 63 km N of Brenas, Puerto Rico
  9. 2.8 109 km N of Suárez, Puerto Rico
  10. 3.1 111 km N of Brenas, Puerto Rico
  11. 2.1 39 km N of Dorado, Puerto Rico
  12. 2.5 93 km N of Brenas, Puerto Rico
  13. 2.2 101 km N of Suárez, Puerto Rico
  14. 2.7 44 km N of San Juan, Puerto Rico
  15. 2.4 63 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.