QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

100 km NNW of San Antonio, Puerto Rico

Yes. A magnitude 3.1 earthquake was recorded 100 km NNW of San Antonio, Puerto Rico, at 9:33 am AST on 19 September 2017 (13:33 UTC), 38 km deep.

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

10 km30 km60 km120 km N Aguadilla Municipio 100 kmIsabela Municipio 107 kmAguada Municipio 108 kmRincón Municipio 110 kmMoca Municipio 113 kmQuebradillas Municipio 114 kmAñasco Municipio 120 kmCamuy Municipio 120 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
38 km below the surface
Felt
no reports yet
Nearest
Aguadilla Municipio, 100 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3250 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 20 km (12 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 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 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 94 km NE of Punta Cana, Dominican Republic · 20 km SW of this epicentre
  2. 6.1 80 km NE of Punta Cana, Dominican Republic · 35 km WSW of this epicentre
  3. 6.0 93 km NNW of San Antonio, Puerto Rico · 33 km E of this epicentre
  4. 6.0 67 km NNW of San Antonio, Puerto Rico · 41 km ESE of this epicentre
  5. 5.7 88 km N of San Antonio, Puerto Rico · 37 km E 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 19.2688, -67.5960. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aguadilla Municipio, PR 100 km (62 mi) SSE earthquakes near Aguadilla Municipio
Isabela Municipio, PR 107 km (66 mi) SE earthquakes near Isabela Municipio
Aguada Municipio, PR 108 km (67 mi) SSE earthquakes near Aguada Municipio
Rincón Municipio, PR 110 km (68 mi) SSE earthquakes near Rincón Municipio
Moca Municipio, PR 113 km (70 mi) SSE earthquakes near Moca Municipio
Quebradillas Municipio, PR 114 km (71 mi) SE earthquakes near Quebradillas 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. 3.2 88 km NE of Punta Cana, Dominican Republic
  2. 3.2 93 km NNW of San Antonio, Puerto Rico
  3. 2.8 71 km NE of Punta Cana, Dominican Republic
  4. 3.1 88 km NE of Punta Cana, Dominican Republic
  5. 2.9 79 km NW of San Antonio, Puerto Rico
  6. 3.1 74 km NNW of San Antonio, Puerto Rico
  7. 3.0 112 km NNE of Punta Cana, Dominican Republic
  8. 3.0 79 km NW of San Antonio, Puerto Rico
  9. 2.7 68 km NW of San Antonio, Puerto Rico
  10. 3.0 101 km NNE of Punta Cana, Dominican Republic
  11. 2.9 61 km NW of San Antonio, Puerto Rico
  12. 2.9 60 km NW of San Antonio, Puerto Rico
  13. 2.1 106 km NNW of San Antonio, Puerto Rico
  14. 2.7 61 km NNW of San Antonio, Puerto Rico
  15. 3.3 Mona Passage

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.