QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Isabela, PR

No earthquake was likely felt in Isabela in the 24 hours to 3:27 pm AST (19:27 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 1.6 earthquake was recorded 4 km (2 mi) north-northwest of Isabela, PR, at 2:06 am AST on 26 December 2018 (06:06 UTC), 17 km deep.

USGS: 3 km NNW of Isabela, Puerto Rico

33 km (20 mi) WNW of Arecibo, PR · 103 km (64 mi) W of San Juan, PR

2:06 am AST, Dec 26, 2018 · · 17 km deep · released about 8.7 lb of TNT

Every earthquake near Isabela Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Isabela Municipio 6 kmAguadilla Municipio 13 kmQuebradillas Municipio 13 kmMoca Municipio 18 kmCamuy Municipio 20 kmSan Sebastián Municipio 23 kmAguada Municipio 24 kmHatillo Municipio 27 kmAñasco Municipio 29 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
2:06 am AST on 26 December 2018 ()
Where
4 km (2 mi) north-northwest of Isabela, PR · earthquakes near Isabela
Magnitude
M 1.6 (md)
Depth
17 km below the surface
Felt
no reports yet
Nearest
Isabela Municipio, 6 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2877 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, 4 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: Mora, Rafael Hernandez, Aceitunas, Quebradillas, Caban, Cacao.

How big was it?

This earthquake released about 8.7 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
  3. Around the size people start to feel M 3.0 110× the energy of this one
  4. This earthquake M 1.6 about 8.7 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 4.3 on 2017-10-14 — about 9,800 times the energy of this one.

Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.7 45 km N of San Antonio, Puerto Rico · 43 km NNW of this epicentre
  2. 7.1 24 km NNW of San Antonio, Puerto Rico · 25 km NW of this epicentre
  3. 6.4 32 km NW of Aguadilla, Puerto Rico · 38 km WNW of this epicentre
  4. 6.3 6 km WNW of Aguadilla, Puerto Rico · 22 km WSW of this epicentre
  5. 6.1 15 km WNW of San Antonio, Puerto Rico · 21 km W 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 18.5328, -67.0338. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Isabela Municipio, PR 6 km (4 mi) SSE earthquakes near Isabela Municipio
Aguadilla Municipio, PR 13 km (8 mi) WSW earthquakes near Aguadilla Municipio
Quebradillas Municipio, PR 13 km (8 mi) ESE earthquakes near Quebradillas Municipio
Moca Municipio, PR 18 km (11 mi) SSW earthquakes near Moca Municipio
Camuy Municipio, PR 20 km (13 mi) ESE earthquakes near Camuy Municipio
San Sebastián Municipio, PR 23 km (15 mi) SSE earthquakes near San Sebastián Municipio

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

Aftershocks so far

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

  1. 3.0 46 km NNW of San Antonio, Puerto Rico
  2. 3.1 48 km N of Hatillo, Puerto Rico
  3. 2.3 19 km NNE of Isabela, Puerto Rico
  4. 2.3 4 km ENE of Hormigueros, Puerto Rico
  5. 2.5 13 km N of Isabela, Puerto Rico
  6. 1.9 11 km ESE of Maricao, Puerto Rico
  7. 1.8 3 km W of Rafael Capo, Puerto Rico
  8. 2.1 2 km NE of San Germán, Puerto Rico
  9. 2.2 4 km ENE of Isabela, Puerto Rico
  10. 2.2 34 km NW of Rincón, Puerto Rico
  11. 2.9 45 km NW of San Antonio, Puerto Rico
  12. 2.1 2 km NNE of Mayagüez, Puerto Rico
  13. 1.8 1 km SE of Piedra Gorda, Puerto Rico
  14. 2.4 13 km N of Carrizales, Puerto Rico
  15. 2.3 24 km NW of Rincón, 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.