QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6md

77 km N of San Juan, Puerto Rico

Yes. A magnitude 3.6 earthquake was recorded 77 km N of San Juan, Puerto Rico, 84 km (52 mi) N of San Juan, PR, at 4:07 am AST on 17 March 2026 (08:07 UTC), 23 km deep.

84 km (52 mi) N of San Juan, PR

· 23 km deep · released about 3.4 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 79 kmToa Baja Municipio 81 kmCataño Municipio 81 kmDorado Municipio 81 kmSan Juan Municipio 82 kmCarolina Municipio 85 kmVega Alta Municipio 88 kmVega Baja Municipio 89 kmRío Grande Municipio 89 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 3.6 (md)
Depth
23 km below the surface
Felt
no reports yet
Nearest
Loíza Municipio, 79 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 169 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 63 km (39 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 3.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 50,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,200× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,600× the energy of this one
  4. This earthquake M 3.6 about 3.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.2× 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 70 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 WSW 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 19.1581, -65.9943. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 79 km (49 mi) S earthquakes near Loíza Municipio
Toa Baja Municipio, PR 81 km (50 mi) SSW earthquakes near Toa Baja Municipio
Cataño Municipio, PR 81 km (50 mi) SSW earthquakes near Cataño Municipio
Dorado Municipio, PR 81 km (50 mi) SSW earthquakes near Dorado Municipio
San Juan Municipio, PR 82 km (51 mi) S earthquakes near San Juan Municipio
Carolina Municipio, PR 85 km (53 mi) S earthquakes near Carolina Municipio

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

Aftershocks so far

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

  1. 3.0 34 km NNE of San Juan, Puerto Rico
  2. 3.1 75 km N of Brenas, Puerto Rico
  3. 3.3 110 km N of Suárez, Puerto Rico
  4. 3.2 93 km N of San Juan, Puerto Rico
  5. 3.3 76 km NNE of Vieques, Puerto Rico
  6. 3.7 117 km N of San Juan, Puerto Rico
  7. 2.9 65 km N of Tierras Nuevas Poniente, Puerto Rico
  8. 3.3 80 km N of San Juan, Puerto Rico
  9. 3.4 75 km N of San Juan, Puerto Rico
  10. 3.4 110 km N of Suárez, Puerto Rico
  11. 3.1 63 km N of San Juan, Puerto Rico
  12. 3.3 109 km N of Suárez, Puerto Rico
  13. 2.9 29 km N of San Juan, Puerto Rico
  14. 3.4 110 km N of Suárez, Puerto Rico
  15. 3.2 44 km NNE of Vieques, 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.