QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

Earthquake near Isabela, PR

No earthquake was likely felt in Isabela in the 24 hours to 11:32 am AST (15:32 UTC). The last one was M 3.4, 31 km (19 mi) N, at 9:00 pm AST on 27 October 2026, estimated intensity II (weak) in town. Every earthquake near Isabela

This page: a magnitude 3.4 earthquake was recorded 41 km (26 mi) north-northwest of Isabela, PR, at 4:49 am AST on 28 February 2023 (08:49 UTC), 6.2 km deep.

USGS: 40 km N of San Antonio, Puerto Rico

4:49 am AST, Feb 28, 2023 · · 6.2 km deep · released about 1.9 tons of TNT

Every earthquake near Isabela Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Aguadilla Municipio 42 kmIsabela Municipio 43 kmQuebradillas Municipio 48 kmCamuy Municipio 53 kmMoca Municipio 54 kmAguada Municipio 54 kmHatillo Municipio 58 kmRincón Municipio 60 kmSan Sebastián Municipio 61 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
4:49 am AST on 28 February 2023 ()
Where
41 km (26 mi) north-northwest of Isabela, PR · earthquakes near Isabela
Magnitude
M 3.4 (md)
Depth
6.2 km below the surface
Felt
no reports yet
Nearest
Aguadilla Municipio, 42 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1352 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 57 km (35 mi) from the epicentre. In Isabela, 41 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: Isabela 41 km, intensity II · Rafael Hernandez 43 km, intensity II · Quebradillas 47 km, intensity II · Aguadilla 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 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 89,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,800× the energy of this one
  4. This earthquake M 3.4 about 1.9 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4× 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 6.0 on 2019-09-24 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.7 45 km N of San Antonio, Puerto Rico · 5 km N of this epicentre
  2. 7.1 24 km NNW of San Antonio, Puerto Rico · 19 km SSW of this epicentre
  3. 6.4 32 km NW of Aguadilla, Puerto Rico · 39 km SW of this epicentre
  4. 6.4 61 km N of Hatillo, Puerto Rico · 38 km ENE of this epicentre
  5. 6.3 6 km WNW of Aguadilla, Puerto Rico · 48 km SSW 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 18.8605, -67.1198. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aguadilla Municipio, PR 42 km (26 mi) S earthquakes near Aguadilla Municipio
Isabela Municipio, PR 43 km (27 mi) SSE earthquakes near Isabela Municipio
Quebradillas Municipio, PR 48 km (30 mi) SSE earthquakes near Quebradillas Municipio
Camuy Municipio, PR 53 km (33 mi) SSE earthquakes near Camuy Municipio
Moca Municipio, PR 54 km (33 mi) S earthquakes near Moca Municipio
Aguada Municipio, PR 54 km (34 mi) S earthquakes near Aguada 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. 3.4 45 km NNW of San Antonio, Puerto Rico
  2. 3.0 38 km NW of Aguadilla, Puerto Rico
  3. 3.3 65 km N of Hatillo, Puerto Rico
  4. 3.1 12 km NW of San Antonio, Puerto Rico
  5. 3.4 49 km NW of Rincón, Puerto Rico
  6. 3.8 66 km N of Hatillo, Puerto Rico
  7. 3.7 60 km N of Isabela, Puerto Rico
  8. 2.9 30 km N of Arecibo, Puerto Rico
  9. 3.1 36 km N of Carrizales, Puerto Rico
  10. 3.6 71 km N of San Antonio, Puerto Rico
  11. 3.0 42 km NNW of San Antonio, Puerto Rico
  12. 3.4 52 km N of Hatillo, Puerto Rico
  13. 3.1 Puerto Rico region
  14. 3.1 54 km N of Hatillo, Puerto Rico
  15. 3.2 42 km NW of San Antonio, 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.