QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

Earthquake near Bairoa, PR

No earthquake was likely felt in Bairoa in the 24 hours to 4:25 pm AST (20:25 UTC). The last one was M 4.1, 82 km (51 mi) ESE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near Bairoa

This page: a magnitude 3.1 earthquake was recorded 5 km (3 mi) north-northeast of Bairoa, PR, at 5:43 pm AST on 16 October 2018 (21:43 UTC), 136 km deep.

USGS: 4 km NNE of Bairoa, Puerto Rico

12 km (8 mi) SSE of San Juan, PR · 8 km (5 mi) N of Caguas, PR

5:43 pm AST, Oct 16, 2018 · · 136 km deep · released about 1,600 lb of TNT

Every earthquake near Bairoa Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Trujillo Alto Municipio 5 kmGurabo Municipio 6 kmCaguas Municipio 10 kmGuaynabo Municipio 10 kmAguas Buenas Municipio 12 kmCarolina Municipio 12 kmSan Juan Municipio 14 kmJuncos Municipio 15 kmCanóvanas Municipio 15 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
5:43 pm AST on 16 October 2018 ()
Where
5 km (3 mi) north-northeast of Bairoa, PR · earthquakes near Bairoa
Magnitude
M 3.1 (md)
Depth
136 km below the surface
Felt
no reports yet
Nearest
Trujillo Alto Municipio, 5 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2882 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. In Bairoa, 5 km away, the estimate is intensity I (not felt). 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: Trujillo Alto, Celada, Caguas, Gurabo, Aguas Buenas, Guaynabo.

How big was it?

This earthquake released about 1,600 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 210,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 9,400× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,700× the energy of this one
  4. This earthquake M 3.1 about 1,600 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.7× 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 4.6 on 2016-12-05 — about 150 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.1 3 km W of Aguas Buenas, Puerto Rico · 12 km WSW of this epicentre
  2. 5.0 3 km N of Brenas, Puerto Rico · 40 km NW 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 18.2990, -66.0271. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Trujillo Alto Municipio, PR 5 km (3 mi) NNE earthquakes near Trujillo Alto Municipio
Gurabo Municipio, PR 6 km (4 mi) ESE earthquakes near Gurabo Municipio
Caguas Municipio, PR 10 km (6 mi) SSW earthquakes near Caguas Municipio
Guaynabo Municipio, PR 10 km (7 mi) WNW earthquakes near Guaynabo Municipio
Aguas Buenas Municipio, PR 12 km (7 mi) WSW earthquakes near Aguas Buenas Municipio
Carolina Municipio, PR 12 km (8 mi) NNE earthquakes near Carolina Municipio

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

Aftershocks so far

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

  1. 2.7 20 km N of Luquillo, Puerto Rico
  2. 1.7 5 km E of Comerío, Puerto Rico
  3. 2.2 34 km N of Loíza, Puerto Rico
  4. 1.7 Puerto Rico region
  5. 2.5 4 km SW of Patillas, Puerto Rico
  6. 1.8 18 km ESE of El Negro, Puerto Rico
  7. 1.9 2 km N of Carolina, Puerto Rico
  8. 1.9 11 km S of Emajagua, Puerto Rico
  9. 2.0 7 km SE of Arroyo, Puerto Rico
  10. 2.1 4 km ESE of Palmarejo, Puerto Rico
  11. 2.1 1 km SSE of G. L. Garcia, Puerto Rico
  12. 2.1 6 km NNW of Loíza, Puerto Rico
  13. 2.5 11 km S of Emajagua, Puerto Rico
  14. 1.9 2 km S of Las Ochenta, Puerto Rico
  15. 2.4 5 km SSW of Central Aguirre, 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.