QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0md

Earthquake near Loíza, PR

No earthquake was likely felt in Loíza in the 24 hours to 10:12 am AST (14:12 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 3.0 earthquake was recorded 24 km (15 mi) north-northwest of Loíza, PR, at 1:13 pm AST on 12 October 2023 (17:13 UTC), 50 km deep. 1 person has reported feeling it to USGS.

USGS: 24 km NNW of Loíza, Puerto Rico

30 km (18 mi) NNE of San Juan, PR · 26 km (16 mi) N of Carolina, PR

1:13 pm AST, Oct 12, 2023 · · 50 km deep · released about 1,000 lb of TNT

Every earthquake near Loíza Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Loíza Municipio 22 kmCarolina Municipio 28 kmSan Juan Municipio 28 kmCataño Municipio 31 kmRío Grande Municipio 33 kmToa Baja Municipio 34 kmTrujillo Alto Municipio 35 kmCanóvanas Municipio 35 kmGuaynabo Municipio 38 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
1:13 pm AST on 12 October 2023 ()
Where
24 km (15 mi) north-northwest of Loíza, PR · earthquakes near Loíza
Magnitude
M 3.0 (md)
Depth
50 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Loíza Municipio, 22 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1126 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 it was probably too small to be felt, even directly above it. In Loíza, 24 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.

Earthquakes near other towns within 30 km: Suárez, San Juan, Vieques, Santa Barbara, Eleanor Roosevelt, San Isidro.

How big was it?

This earthquake released about 1,000 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 330,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 15,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 10,000× the energy of this one
  4. This earthquake M 3.0 about 1,000 lb of TNT

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 2018-12-09 — about 120 times the energy of this one.

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

  1. 5.1 3 km W of Aguas Buenas, Puerto Rico · 47 km SSW of this epicentre
  2. 5.0 3 km N of Brenas, Puerto Rico · 45 km WSW 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 18.6443, -65.9390. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Loíza Municipio, PR 22 km (14 mi) S earthquakes near Loíza Municipio
Carolina Municipio, PR 28 km (17 mi) S earthquakes near Carolina Municipio
San Juan Municipio, PR 28 km (18 mi) SSW earthquakes near San Juan Municipio
Cataño Municipio, PR 31 km (19 mi) SW earthquakes near Cataño Municipio
Río Grande Municipio, PR 33 km (21 mi) SSE earthquakes near Río Grande Municipio
Toa Baja Municipio, PR 34 km (21 mi) SW earthquakes near Toa Baja Municipio

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

Aftershocks so far

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

  1. 3.7 4 km SW of Ramos, Puerto Rico
  2. 3.3 6 km NNW of Trujillo Alto, Puerto Rico
  3. 3.1 21 km N of Brenas, Puerto Rico
  4. 3.3 29 km NNE of Suárez, Puerto Rico
  5. 3.2 55 km N of Loíza, Puerto Rico
  6. 3.2 64 km N of San Juan, Puerto Rico
  7. 3.2 50 km N of Suárez, Puerto Rico
  8. 2.7 3 km SE of Pájaros, Puerto Rico
  9. 2.4 5 km WNW of Aguas Buenas, Puerto Rico
  10. 3.0 27 km NNW of Brenas, Puerto Rico
  11. 3.1 65 km N of San Juan, Puerto Rico
  12. 3.9 52 km N of Suárez, Puerto Rico
  13. 2.9 4 km NNW of Santa Barbara, Puerto Rico
  14. 2.9 42 km N of San Juan, Puerto Rico
  15. 3.1 37 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.