QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near San Sebastián, PR

No earthquake was likely felt in San Sebastián in the 24 hours to 11:33 am AST (15:33 UTC). The last one was M 3.4, 50 km (31 mi) N, at 9:00 pm AST on 27 October 2026, estimated intensity II (weak) in town. Every earthquake near San Sebastián

This page: a magnitude 1.8 earthquake was recorded 6 km (4 mi) northeast of San Sebastián, PR, at 7:11 pm AST on 6 September 2019 (23:11 UTC), 17 km deep.

USGS: 6 km NE of San Sebastián, Puerto Rico

94 km (59 mi) W of San Juan, PR · 25 km (15 mi) WSW of Arecibo, PR

7:11 pm AST, Sep 6, 2019 · · 17 km deep · released about 15 lb of TNT

Every earthquake near San Sebastián Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Sebastián Municipio 6 kmQuebradillas Municipio 10 kmCamuy Municipio 12 kmIsabela Municipio 13 kmMoca Municipio 13 kmLares Municipio 15 kmLas Marías Municipio 17 kmHatillo Municipio 18 kmAñasco Municipio 21 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
7:11 pm AST on 6 September 2019 ()
Where
6 km (4 mi) northeast of San Sebastián, PR · earthquakes near San Sebastián
Magnitude
M 1.8 (md)
Depth
17 km below the surface
Felt
no reports yet
Nearest
San Sebastián Municipio, 6 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2622 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 San Sebastián, 6 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: Cacao, Juncal, Piedra Gorda, Quebradillas, Mora, Lares.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 5,600 times the energy of this one.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 24 km NNW of San Antonio, Puerto Rico · 43 km NW of this epicentre
  2. 6.3 6 km WNW of Aguadilla, Puerto Rico · 28 km WNW of this epicentre
  3. 6.1 15 km WNW of San Antonio, Puerto Rico · 35 km WNW of this epicentre
  4. 6.1 18 km NNW of San Antonio, Puerto Rico · 37 km NW of this epicentre
  5. 5.8 12 km N of Garrochales, Puerto Rico · 46 km ENE 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 18.3815, -66.9563. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Sebastián Municipio, PR 6 km (4 mi) SSW earthquakes near San Sebastián Municipio
Quebradillas Municipio, PR 10 km (6 mi) NNE earthquakes near Quebradillas Municipio
Camuy Municipio, PR 12 km (8 mi) NE earthquakes near Camuy Municipio
Isabela Municipio, PR 13 km (8 mi) NNW earthquakes near Isabela Municipio
Moca Municipio, PR 13 km (8 mi) W earthquakes near Moca Municipio
Lares Municipio, PR 15 km (9 mi) SE earthquakes near Lares Municipio

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

Aftershocks so far

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

  1. 2.5 4 km SSE of Cacao, Puerto Rico
  2. 2.3 28 km NW of San Antonio, Puerto Rico
  3. 1.9 3 km SW of San Sebastián, Puerto Rico
  4. 2.7 36 km NNE of Isabela, Puerto Rico
  5. 2.6 24 km N of San Antonio, Puerto Rico
  6. 2.3 25 km N of Isabela, Puerto Rico
  7. 1.5 2 km E of Mayagüez, Puerto Rico
  8. 2.4 31 km NNW of San Antonio, Puerto Rico
  9. 2.9 28 km N of Isabela, Puerto Rico
  10. 2.1 11 km NNE of Garrochales, Puerto Rico
  11. 2.1 2 km NE of Jayuya, Puerto Rico
  12. 2.5 9 km N of Isabela, Puerto Rico
  13. 1.8 8 km ENE of Maricao, Puerto Rico
  14. 1.9 3 km SSW of Maricao, Puerto Rico
  15. 2.2 18 km N of Hatillo, 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.