QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5md

93 km N of Suárez, Puerto Rico

Yes. A magnitude 3.5 earthquake was recorded 93 km N of Suárez, Puerto Rico, at 10:22 pm AST on 12 October 2021 (02:22 UTC), 41 km deep. 1 person has reported feeling it to USGS.

· 41 km deep · released about 2.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 94 kmFajardo Municipio 98 kmRío Grande Municipio 99 kmLuquillo Municipio 100 kmCarolina Municipio 100 kmSan Juan Municipio 101 kmCataño Municipio 102 kmToa Baja Municipio 103 kmDorado Municipio 105 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 3.5 (md)
Depth
41 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Loíza Municipio, 94 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1556 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 44 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 2.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 75,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 3,300× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,400× the energy of this one
  4. This earthquake M 3.5 about 2.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4.7× 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 4.5 on 2018-03-06 — about 38 times the energy of this one.

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

  1. 5.1 122 km NNE of Vieques, Puerto Rico · 45 km ENE of this epicentre
  2. 5.1 92 km N of Suárez, Puerto Rico · 1 km WSW of this epicentre
  3. 5.0 73 km NNE of Vieques, Puerto Rico · 37 km SE 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 19.2640, -65.7130. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 94 km (59 mi) SSW earthquakes near Loíza Municipio
Fajardo Municipio, PR 98 km (61 mi) S earthquakes near Fajardo Municipio
Río Grande Municipio, PR 99 km (62 mi) S earthquakes near Río Grande Municipio
Luquillo Municipio, PR 100 km (62 mi) S earthquakes near Luquillo Municipio
Carolina Municipio, PR 100 km (62 mi) SSW earthquakes near Carolina Municipio
San Juan Municipio, PR 101 km (63 mi) SSW earthquakes near San Juan Municipio

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

Aftershocks so far

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

  1. 3.2 71 km N of San Juan, Puerto Rico
  2. 3.0 67 km N of San Juan, Puerto Rico
  3. 3.5 Puerto Rico region
  4. 3.6 102 km NNE of Suárez, Puerto Rico
  5. 3.3 100 km N of San Juan, Puerto Rico
  6. 3.6 83 km N of Culebra, Puerto Rico
  7. 3.1 Puerto Rico region
  8. 3.2 60 km N of Loíza, Puerto Rico
  9. 3.7 126 km NNE of Suárez, Puerto Rico
  10. 2.7 71 km NNE of San Juan, Puerto Rico
  11. 3.5 84 km NNE of Luquillo, Puerto Rico
  12. 3.9 78 km N of San Juan, Puerto Rico
  13. 3.6 Puerto Rico region
  14. 3.4 86 km N of Culebra, Puerto Rico
  15. 3.3 129 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.