QuakeIndex

Earthquake · reviewed by a seismologist

M 3.2md

Earthquake near Humacao, PR

No earthquake was likely felt in Humacao in the 24 hours to 3:24 am AST (07:24 UTC). The last one was M 4.1, 56 km (35 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 Humacao

This page: a magnitude 3.2 earthquake was recorded 48 km (30 mi) south-southeast of Humacao, PR, at 8:16 pm AST on 4 October 2023 (00:16 UTC), 38 km deep.

USGS: 36 km SE of Emajagua, Puerto Rico

85 km (53 mi) SSE of San Juan, PR

8:16 pm AST, Oct 4, 2023 · · 38 km deep · released about 1,700 lb of TNT

Every earthquake near Humacao Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Maunabo Municipio 38 kmYabucoa Municipio 41 kmPatillas Municipio 45 kmHumacao Municipio 45 kmVieques Municipio 48 kmArroyo Municipio 48 kmNaguabo Municipio 52 kmLas Piedras Municipio 54 kmSan Lorenzo Municipio 56 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
8:16 pm AST on 4 October 2023 ()
Where
48 km (30 mi) south-southeast of Humacao, PR · earthquakes near Humacao
Magnitude
M 3.2 (md)
Depth
38 km below the surface
Felt
no reports yet
Nearest
Maunabo Municipio, 38 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1134 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 24 km (15 mi) from the epicentre. In Humacao, 48 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.

How big was it?

This earthquake released about 1,700 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 6.7 200,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 9,100× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,500× the energy of this one
  4. This earthquake M 3.2 about 1,700 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 4.8 on 2021-10-08 — about 290 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.3 68 km SSE of Emajagua, Puerto Rico · 40 km S 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 17.7502, -65.6535. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Maunabo Municipio, PR 38 km (24 mi) NW earthquakes near Maunabo Municipio
Yabucoa Municipio, PR 41 km (25 mi) NNW earthquakes near Yabucoa Municipio
Patillas Municipio, PR 45 km (28 mi) NW earthquakes near Patillas Municipio
Humacao Municipio, PR 45 km (28 mi) NNW earthquakes near Humacao Municipio
Vieques Municipio, PR 48 km (30 mi) NNE earthquakes near Vieques Municipio
Arroyo Municipio, PR 48 km (30 mi) WNW earthquakes near Arroyo 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. 2.4 4 km SE of Arroyo, Puerto Rico
  2. 2.6 15 km ESE of Emajagua, Puerto Rico
  3. 2.9 13 km E of El Negro, Puerto Rico
  4. 2.6 1 km W of Punta Santiago, Puerto Rico
  5. 1.9 15 km ESE of El Negro, Puerto Rico
  6. 2.3 11 km S of Arroyo, Puerto Rico
  7. 2.3 11 km S of Arroyo, Puerto Rico
  8. 2.0 13 km SE of El Negro, Puerto Rico
  9. 2.8 4 km S of Bajandas, Puerto Rico
  10. 2.6 4 km S of Bajandas, Puerto Rico
  11. 2.7 4 km S of Bajandas, Puerto Rico
  12. 2.9 15 km S of Esperanza, Puerto Rico
  13. 2.3 6 km SSE of Bajandas, Puerto Rico
  14. 3.4 29 km SSW of Esperanza, Puerto Rico
  15. 3.6 4 km SSW of Bajandas, 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.