QuakeIndex

Earthquake · reviewed by a seismologist

M 3.2md

Earthquake near Isabel Segunda, PR

No earthquake was likely felt in Isabel Segunda in the 24 hours to 3:33 pm AST (19:33 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 3.2 earthquake was recorded 21 km (13 mi) south of Isabel Segunda, PR, at 7:41 pm AST on 8 August 2017 (23:41 UTC), 16 km deep. 3 people have reported feeling it to USGS.

USGS: Puerto Rico region

80 km (50 mi) SE of San Juan, PR

7:41 pm AST, Aug 8, 2017 · · 16 km deep · released about 2,000 lb of TNT

Every earthquake near Isabel Segunda Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Vieques Municipio 18 kmCeiba Municipio 36 kmHumacao Municipio 39 kmNaguabo Municipio 40 kmCulebra Municipio 43 kmYabucoa Municipio 43 kmMaunabo Municipio 46 kmFajardo Municipio 49 kmLas Piedras Municipio 50 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
7:41 pm AST on 8 August 2017 ()
Where
21 km (13 mi) south of Isabel Segunda, PR · earthquakes near Isabel Segunda
Magnitude
M 3.2 (md)
Depth
16 km below the surface
Felt
3 reports · strongest reported intensity III
Nearest
Vieques Municipio, 18 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1557 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 44 km (27 mi) from the epicentre. In Isabel Segunda, 21 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.

Likely felt in: Esperanza 15 km, intensity II · Isabel Segunda 21 km, intensity II · Aguas Claras 38 km, intensity II · Culebra 41 km, intensity II · Humacao 44 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 2,000 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 6.7 170,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 7,700× the energy of this one
  3. Magna, Utah 2020 M 5.7 5,400× the energy of this one
  4. This earthquake M 3.2 about 2,000 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 2.1× 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 in our catalogue was M 4.6 on 2016-12-05 — about 120 times the energy of this one.

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 17.9651, -65.4618. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Vieques Municipio, PR 18 km (11 mi) N earthquakes near Vieques Municipio
Ceiba Municipio, PR 36 km (22 mi) NNW earthquakes near Ceiba Municipio
Humacao Municipio, PR 39 km (24 mi) WNW earthquakes near Humacao Municipio
Naguabo Municipio, PR 40 km (25 mi) NW earthquakes near Naguabo Municipio
Culebra Municipio, PR 43 km (27 mi) NNE earthquakes near Culebra Municipio
Yabucoa Municipio, PR 43 km (27 mi) WNW earthquakes near Yabucoa Municipio

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

Aftershocks so far

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

  1. 1.9 9 km S of Emajagua, Puerto Rico
  2. 2.7 8 km SSW of Emajagua, Puerto Rico
  3. 1.7 10 km S of Emajagua, Puerto Rico
  4. 2.9 8 km SE of Culebra, Puerto Rico
  5. 3.1 36 km NW of Saint Croix, U.S. Virgin Islands
  6. 3.1 6 km S of Esperanza, Puerto Rico
  7. 2.7 36 km S of Esperanza, Puerto Rico
  8. 2.9 1 km S of Esperanza, Puerto Rico
  9. 2.7 13 km W of Esperanza, Puerto Rico
  10. 2.3 2 km ESE of Humacao, Puerto Rico
  11. 3.1 4 km W of Esperanza, Puerto Rico
  12. 2.8 19 km SSW of Esperanza, Puerto Rico
  13. 3.1 4 km SSE of Palo Seco, Puerto Rico
  14. 3.3 9 km SE of Esperanza, Puerto Rico
  15. 2.5 21 km SE of Esperanza, 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.