QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5md

Earthquake near Isabel Segunda, PR

No earthquake was likely felt in Isabel Segunda in the 24 hours to 7:20 pm AST (23:20 UTC). The last one was M 2.9, 26 km (16 mi) SSE, at 12:08 pm AST on 29 October 2026, estimated intensity II (weak) in town. Every earthquake near Isabel Segunda

This page: a magnitude 2.5 earthquake was recorded 8 km (5 mi) north-northwest of Isabel Segunda, PR, at 9:22 pm AST on 6 August 2018 (01:22 UTC), 115 km deep.

USGS: 8 km NNW of Isabel Segunda, Puerto Rico

66 km (41 mi) ESE of San Juan, PR · 58 km (36 mi) ESE of Carolina, PR

9:22 pm AST, Aug 6, 2018 · · 115 km deep · released about 140 lb of TNT

Every earthquake near Isabel Segunda Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Vieques Municipio 11 kmCeiba Municipio 16 kmCulebra Municipio 21 kmFajardo Municipio 22 kmNaguabo Municipio 28 kmLuquillo Municipio 30 kmHumacao Municipio 34 kmRío Grande Municipio 38 kmLas Piedras Municipio 42 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
9:22 pm AST on 6 August 2018 ()
Where
8 km (5 mi) north-northwest of Isabel Segunda, PR · earthquakes near Isabel Segunda
Magnitude
M 2.5 (md)
Depth
115 km below the surface
Felt
no reports yet
Nearest
Vieques Municipio, 11 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2947 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 Isabel Segunda, 8 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: Esperanza, Aguas Claras, Luis M. Cintron, Culebra, Daguao, Fajardo.

How big was it?

This earthquake released about 140 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 110,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 75,000× the energy of this one
  3. Around the size people start to feel M 3.0 6.7× the energy of this one
  4. This earthquake M 2.5 about 140 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 2016-09-02 — about 600 times the energy of this one.

Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.

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 18.2170, -65.4748. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Vieques Municipio, PR 11 km (7 mi) SSE earthquakes near Vieques Municipio
Ceiba Municipio, PR 16 km (10 mi) WNW earthquakes near Ceiba Municipio
Culebra Municipio, PR 21 km (13 mi) NE earthquakes near Culebra Municipio
Fajardo Municipio, PR 22 km (14 mi) NNW earthquakes near Fajardo Municipio
Naguabo Municipio, PR 28 km (17 mi) W earthquakes near Naguabo Municipio
Luquillo Municipio, PR 30 km (19 mi) NW earthquakes near Luquillo Municipio

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

Aftershocks so far

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

  1. 2.3 35 km NE of Luquillo, Puerto Rico
  2. 3.1 29 km ESE of Esperanza, Puerto Rico
  3. 2.6 5 km SE of Esperanza, Puerto Rico
  4. 2.9 39 km NNW of Culebra, Puerto Rico
  5. 1.9 21 km SSW of Esperanza, Puerto Rico
  6. 2.9 9 km ENE of Isabel Segunda, Puerto Rico
  7. 2.7 20 km N of Luquillo, Puerto Rico
  8. 2.8 31 km NNE of Luquillo, Puerto Rico
  9. 1.8 18 km ESE of El Negro, Puerto Rico
  10. 2.2 Puerto Rico region
  11. 2.6 3 km NNW of Benitez, Puerto Rico
  12. 2.6 14 km SW of Esperanza, Puerto Rico
  13. 1.9 17 km SE of Esperanza, Puerto Rico
  14. 2.9 41 km ESE of Esperanza, Puerto Rico
  15. 2.8 23 km NNE of Luquillo, 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.