QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7md

Earthquake near Isabel Segunda, PR

No earthquake was likely felt in Isabel Segunda in the 24 hours to 4:30 pm AST (20:30 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 3.7 earthquake was recorded 15 km (9 mi) north of Isabel Segunda, PR, at 4:05 pm AST on 4 September 2020 (20:05 UTC), 116 km deep. 1 person has reported feeling it to USGS.

USGS: 14 km N of Isabel Segunda, Puerto Rico

65 km (41 mi) ESE of San Juan, PR · 57 km (35 mi) ESE of Carolina, PR

4:05 pm AST, Sep 4, 2020 · · 116 km deep · released about 5.2 tons of TNT

Every earthquake near Isabel Segunda Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Culebra Municipio 17 kmCeiba Municipio 18 kmVieques Municipio 18 kmFajardo Municipio 18 kmLuquillo Municipio 28 kmNaguabo Municipio 30 kmRío Grande Municipio 37 kmHumacao Municipio 38 kmLas Piedras Municipio 45 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
4:05 pm AST on 4 September 2020 ()
Where
15 km (9 mi) north of Isabel Segunda, PR · earthquakes near Isabel Segunda
Magnitude
M 3.7 (md)
Depth
116 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Culebra Municipio, 17 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1556 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 Isabel Segunda, 15 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: Culebra, Luis M. Cintron, Esperanza, Aguas Claras, Fajardo, Daguao.

How big was it?

This earthquake released about 5.2 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 33,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,500× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,000× the energy of this one
  4. This earthquake M 3.7 about 5.2 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 11× 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 4.3 on 2016-09-02 — about 8.2 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 18.2838, -65.4576. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Culebra Municipio, PR 17 km (10 mi) ENE earthquakes near Culebra Municipio
Ceiba Municipio, PR 18 km (11 mi) W earthquakes near Ceiba Municipio
Vieques Municipio, PR 18 km (11 mi) S earthquakes near Vieques Municipio
Fajardo Municipio, PR 18 km (11 mi) NW earthquakes near Fajardo Municipio
Luquillo Municipio, PR 28 km (18 mi) WNW earthquakes near Luquillo Municipio
Naguabo Municipio, PR 30 km (19 mi) WSW earthquakes near Naguabo Municipio

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

Aftershocks so far

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

  1. 3.4 23 km SSE of Esperanza, Puerto Rico
  2. 3.0 11 km W of Esperanza, Puerto Rico
  3. 3.3 11 km SW of Esperanza, Puerto Rico
  4. 3.7 9 km SW of Esperanza, Puerto Rico
  5. 3.0 22 km NNE of Luquillo, Puerto Rico
  6. 2.7 22 km SE of El Negro, Puerto Rico
  7. 3.4 26 km S of Esperanza, Puerto Rico
  8. 2.6 19 km NNW of Culebra, Puerto Rico
  9. 3.4 7 km NW of Culebra, Puerto Rico
  10. 2.9 16 km NNE of Suárez, Puerto Rico
  11. 3.4 44 km N of Culebra, Puerto Rico
  12. 3.8 39 km N of Culebra, Puerto Rico
  13. 2.2 5 km ESE of Aguas Claras, Puerto Rico
  14. 1.8 3 km E of El Negro, Puerto Rico
  15. 2.8 22 km SSW 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.