QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

101 km N of Isabela, Puerto Rico

Yes. A magnitude 3.4 earthquake was recorded 101 km N of Isabela, Puerto Rico, at 9:56 pm AST on 28 June 2017 (01:56 UTC), 10 km deep.

· 10 km deep · released about 2 tons of TNT

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10 km30 km60 km120 km N Isabela Municipio 104 kmAguadilla Municipio 104 kmQuebradillas Municipio 106 kmCamuy Municipio 110 kmHatillo Municipio 112 kmMoca Municipio 115 kmAguada Municipio 116 kmArecibo Municipio 117 kmBarceloneta Municipio 118 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 3.4 (md)
Depth
10 km below the surface
Felt
no reports yet
Nearest
Isabela Municipio, 104 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3333 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. 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 2 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 86,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 3,800× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,700× the energy of this one
  4. This earthquake M 3.4 about 2 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4.1× 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 4.0 on 2016-02-13 — about 7.7 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. 6.4 61 km N of Hatillo, Puerto Rico · 49 km SSE of this epicentre
  2. 6.0 93 km NNW of San Antonio, Puerto Rico · 25 km WSW of this epicentre
  3. 6.0 81 km N of Isabela, Puerto Rico · 25 km SE of this epicentre
  4. 6.0 67 km NNW of San Antonio, Puerto Rico · 42 km SSW of this epicentre
  5. 5.7 88 km N of San Antonio, Puerto Rico · 24 km SW 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 19.4143, -67.0691. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Isabela Municipio, PR 104 km (64 mi) S earthquakes near Isabela Municipio
Aguadilla Municipio, PR 104 km (65 mi) S earthquakes near Aguadilla Municipio
Quebradillas Municipio, PR 106 km (66 mi) S earthquakes near Quebradillas Municipio
Camuy Municipio, PR 110 km (68 mi) SSE earthquakes near Camuy Municipio
Hatillo Municipio, PR 112 km (70 mi) SSE earthquakes near Hatillo Municipio
Moca Municipio, PR 115 km (72 mi) S earthquakes near Moca Municipio

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

Aftershocks so far

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

  1. 2.3 57 km N of Isabela, Puerto Rico
  2. 3.6 57 km N of Isabela, Puerto Rico
  3. 2.6 55 km N of Isabela, Puerto Rico
  4. 2.6 76 km N of Isabela, Puerto Rico
  5. 2.5 89 km NNW of San Antonio, Puerto Rico
  6. 2.7 63 km N of Isabela, Puerto Rico
  7. 3.2 119 km NNW of San Antonio, Puerto Rico
  8. 3.0 133 km N of Isabela, Puerto Rico
  9. 3.3 99 km N of San Antonio, Puerto Rico
  10. 3.3 98 km NNW of San Antonio, Puerto Rico
  11. 3.3 99 km NNW of San Antonio, Puerto Rico
  12. 2.9 93 km N of San Antonio, Puerto Rico
  13. 2.9 95 km NNW of San Antonio, Puerto Rico
  14. 3.3 91 km NNW of San Antonio, Puerto Rico
  15. 3.0 92 km NNW 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.