QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3md

Earthquake near Loíza, PR

No earthquake was likely felt in Loíza in the 24 hours to 4:41 pm AST (20:41 UTC). The last one was M 4.1, 78 km (48 mi) SE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near Loíza

This page: a magnitude 3.3 earthquake was recorded 48 km (30 mi) north of Loíza, PR, at 1:27 am AST on 27 September 2024 (05:27 UTC), 11 km deep.

USGS: 48 km N of Suárez, Puerto Rico

56 km (35 mi) NNE of San Juan, PR · 52 km (33 mi) NNE of Carolina, PR

1:27 am AST, Sep 27, 2024 · · 11 km deep · released about 1.4 tons of TNT

Every earthquake near Loíza Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 48 kmCarolina Municipio 54 kmSan Juan Municipio 55 kmRío Grande Municipio 55 kmCataño Municipio 57 kmLuquillo Municipio 57 kmToa Baja Municipio 58 kmCanóvanas Municipio 60 kmFajardo Municipio 60 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
1:27 am AST on 27 September 2024 ()
Where
48 km (30 mi) north of Loíza, PR · earthquakes near Loíza
Magnitude
M 3.3 (md)
Depth
11 km below the surface
Felt
no reports yet
Nearest
Loíza Municipio, 48 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 776 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 52 km (32 mi) from the epicentre. In Loíza, 48 km away, the estimate is intensity II (weak). 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.

Likely felt in: Loíza 48 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 120,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,200× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,700× the energy of this one
  4. This earthquake M 3.3 about 1.4 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3× 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 170 times the energy of this one.

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

  1. 5.1 92 km N of Suárez, Puerto Rico · 46 km NNE of this epicentre
  2. 5.0 73 km NNE of Vieques, Puerto Rico · 40 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 18.8655, -65.8467. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 48 km (30 mi) SSW earthquakes near Loíza Municipio
Carolina Municipio, PR 54 km (33 mi) SSW earthquakes near Carolina Municipio
San Juan Municipio, PR 55 km (34 mi) SSW earthquakes near San Juan Municipio
Río Grande Municipio, PR 55 km (34 mi) S earthquakes near Río Grande Municipio
Cataño Municipio, PR 57 km (35 mi) SW earthquakes near Cataño Municipio
Luquillo Municipio, PR 57 km (36 mi) SSE earthquakes near Luquillo Municipio

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

Aftershocks so far

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

  1. 3.0 59 km NNW of Culebra, Puerto Rico
  2. 3.4 33 km NNE of Vieques, Puerto Rico
  3. 3.1 58 km NNE of Luquillo, Puerto Rico
  4. 3.3 63 km N of Loíza, Puerto Rico
  5. 2.9 34 km N of San Juan, Puerto Rico
  6. 3.3 77 km NNE of Vieques, Puerto Rico
  7. 2.9 53 km NNE of Luquillo, Puerto Rico
  8. 3.2 9 km NNE of San Juan, Puerto Rico
  9. 2.9 44 km NNE of Luquillo, Puerto Rico
  10. 3.2 67 km N of Culebra, Puerto Rico
  11. 3.0 56 km NNE of Luquillo, Puerto Rico
  12. 2.7 56 km NNE of Luquillo, Puerto Rico
  13. 3.1 75 km N of San Juan, Puerto Rico
  14. 3.5 82 km NNE of Vieques, Puerto Rico
  15. 3.4 42 km NNW of Culebra, 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.