QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

100 km N of Isabela, Puerto Rico

Yes. A magnitude 3.1 earthquake was recorded 100 km N of Isabela, Puerto Rico, at 1:35 pm AST on 4 April 2018 (17:35 UTC), 70 km deep.

· 70 km deep · released about 1,400 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Aguadilla Municipio 102 kmIsabela Municipio 103 kmQuebradillas Municipio 107 kmCamuy Municipio 111 kmHatillo Municipio 113 kmAguada Municipio 114 kmMoca Municipio 114 kmRincón Municipio 118 kmArecibo Municipio 119 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
Magnitude
M 3.1 (md)
Depth
70 km below the surface
Felt
no reports yet
Nearest
Aguadilla Municipio, 102 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3143 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. 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 1,400 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 230,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 10,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,400× the energy of this one
  4. This earthquake M 3.1 about 1,400 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.5× 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 4.2 on 2017-08-27 — about 39 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 93 km NNW of San Antonio, Puerto Rico · 15 km SW of this epicentre
  2. 6.0 81 km N of Isabela, Puerto Rico · 32 km SE of this epicentre
  3. 6.0 67 km NNW of San Antonio, Puerto Rico · 36 km SSW of this epicentre
  4. 5.7 88 km N of San Antonio, Puerto Rico · 15 km SSW of this epicentre
  5. 5.5 65 km N of Isabela, Puerto Rico · 35 km SSE 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 19.3978, -67.1710. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aguadilla Municipio, PR 102 km (63 mi) S earthquakes near Aguadilla Municipio
Isabela Municipio, PR 103 km (64 mi) S earthquakes near Isabela Municipio
Quebradillas Municipio, PR 107 km (66 mi) SSE earthquakes near Quebradillas Municipio
Camuy Municipio, PR 111 km (69 mi) SSE earthquakes near Camuy Municipio
Hatillo Municipio, PR 113 km (70 mi) SSE earthquakes near Hatillo Municipio
Aguada Municipio, PR 114 km (71 mi) S earthquakes near Aguada Municipio

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

Aftershocks so far

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

  1. 2.9 85 km NNW of San Antonio, Puerto Rico
  2. 3.1 102 km N of San Antonio, Puerto Rico
  3. 2.9 66 km N of Isabela, Puerto Rico
  4. 2.9 114 km NNW of San Antonio, Puerto Rico
  5. 2.9 71 km N of San Antonio, Puerto Rico
  6. 2.8 65 km N of Isabela, Puerto Rico
  7. 2.8 57 km N of Isabela, Puerto Rico
  8. 2.7 61 km NNW of San Antonio, Puerto Rico
  9. 2.8 89 km N of Isabela, Puerto Rico
  10. 2.6 59 km NNE of Isabela, Puerto Rico
  11. 3.1 96 km NNW of San Antonio, Puerto Rico
  12. 3.0 91 km N of Isabela, Puerto Rico
  13. 3.0 121 km NNW of San Antonio, Puerto Rico
  14. 3.0 117 km NNW of San Antonio, Puerto Rico
  15. 2.8 61 km N of Isabela, 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.