QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4Md

Earthquake near Isabela, PR

No earthquake was likely felt in Isabela in the 24 hours to 12:40 am AST (04:40 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 2.4 earthquake was recorded 29 km (18 mi) north of Isabela, PR, at 12:22 am AST on 21 September 2016 (04:22 UTC), 52 km deep.

USGS: 29 km N of Isabela, Puerto Rico

44 km (27 mi) NW of Arecibo, PR · 106 km (66 mi) WNW of San Juan, PR

12:22 am AST, Sep 21, 2016 · · 52 km deep · released about 120 lb of TNT

Every earthquake near Isabela Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Isabela Municipio 31 kmQuebradillas Municipio 34 kmAguadilla Municipio 35 kmCamuy Municipio 38 kmHatillo Municipio 42 kmMoca Municipio 44 kmAguada Municipio 48 kmSan Sebastián Municipio 48 kmArecibo Municipio 50 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
12:22 am AST on 21 September 2016 ()
Where
29 km (18 mi) north of Isabela, PR · earthquakes near Isabela
Magnitude
M 2.4 (Md)
Depth
52 km below the surface
Felt
no reports yet
Nearest
Isabela Municipio, 31 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3704 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Isabela, 29 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.

How big was it?

This earthquake released about 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
  3. Around the size people start to feel M 3.0 7.9× the energy of this one
  4. This earthquake M 2.4 about 120 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 18 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.7 45 km N of San Antonio, Puerto Rico · 20 km NW of this epicentre
  2. 7.1 24 km NNW of San Antonio, Puerto Rico · 21 km WSW of this epicentre
  3. 6.4 32 km NW of Aguadilla, Puerto Rico · 44 km WSW of this epicentre
  4. 6.4 61 km N of Hatillo, Puerto Rico · 37 km NNE of this epicentre
  5. 6.3 6 km WNW of Aguadilla, Puerto Rico · 43 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 18.7637, -66.9972. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Isabela Municipio, PR 31 km (19 mi) S earthquakes near Isabela Municipio
Quebradillas Municipio, PR 34 km (21 mi) SSE earthquakes near Quebradillas Municipio
Aguadilla Municipio, PR 35 km (22 mi) SSW earthquakes near Aguadilla Municipio
Camuy Municipio, PR 38 km (24 mi) SSE earthquakes near Camuy Municipio
Hatillo Municipio, PR 42 km (26 mi) SSE earthquakes near Hatillo Municipio
Moca Municipio, PR 44 km (27 mi) SSW earthquakes near Moca Municipio

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

Aftershocks so far

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

  1. 2.7 18 km NNE of Carrizales, Puerto Rico
  2. 2.7 14 km N of Arecibo, Puerto Rico
  3. 3.0 46 km NW of San Antonio, Puerto Rico
  4. 2.4 13 km N of Isabela, Puerto Rico
  5. 2.8 48 km NW of San Antonio, Puerto Rico
  6. 3.0 14 km NNE of Arecibo, Puerto Rico
  7. 2.8 21 km NNE of Arecibo, Puerto Rico
  8. 2.7 35 km NW of Aguadilla, Puerto Rico
  9. 2.3 14 km N of Arecibo, Puerto Rico
  10. 2.9 33 km NW of San Antonio, Puerto Rico
  11. 2.4 Puerto Rico region
  12. 2.3 15 km NNE of Isabela, Puerto Rico
  13. 3.0 60 km N of Hatillo, Puerto Rico
  14. 3.1 23 km NNW of Camuy, Puerto Rico
  15. 2.8 25 km NNE of Arecibo, 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.