QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9md

Earthquake near Monte Grande, PR

No earthquake was likely felt in Monte Grande in the 24 hours to 4:26 pm AST (20:26 UTC). The last one was M 2.1, 9 km (6 mi) S, at 11:57 pm AST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Monte Grande

This page: a magnitude 2.9 earthquake was recorded 3 km (2 mi) south of Monte Grande, PR, at 11:46 pm AST on 22 October 2023 (03:46 UTC), 20 km deep.

USGS: 3 km S of Monte Grande, Puerto Rico

16 km (10 mi) SSE of Mayagüez, PR · 116 km (72 mi) WSW of San Juan, PR

11:46 pm AST, Oct 22, 2023 · · 20 km deep · released about 570 lb of TNT

Every earthquake near Monte Grande Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Hormigueros Municipio 8 kmSan Germán Municipio 9 kmCabo Rojo Municipio 11 kmLajas Municipio 11 kmSabana Grande Municipio 17 kmMaricao Municipio 22 kmGuánica Municipio 23 kmLas Marías Municipio 23 kmAñasco Municipio 25 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
11:46 pm AST on 22 October 2023 ()
Where
3 km (2 mi) south of Monte Grande, PR · earthquakes near Monte Grande
Magnitude
M 2.9 (md)
Depth
20 km below the surface
Felt
no reports yet
Nearest
Hormigueros Municipio, 8 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1115 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 21 km (13 mi) from the epicentre. In Monte Grande, 3 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: San Germán 7 km, intensity II · Puerto Real 9 km, intensity II · Pole Ojea 13 km, intensity II · Mayagüez 16 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 570 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 27,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 19,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.7× the energy of this one
  4. This earthquake M 2.9 about 570 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 6.4 on 2020-01-07 — about 210,000 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 6.3 6 km WNW of Aguadilla, Puerto Rico · 44 km NNW of this epicentre
  2. 5.8 4 km E of Moca, Puerto Rico · 38 km N of this epicentre
  3. 5.2 19 km SW of Stella, Puerto Rico · 32 km WNW of this epicentre
  4. 5.1 21 km SW of Stella, Puerto Rico · 31 km WNW 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 18.0600, -67.1023. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Hormigueros Municipio, PR 8 km (5 mi) N earthquakes near Hormigueros Municipio
San Germán Municipio, PR 9 km (5 mi) NE earthquakes near San Germán Municipio
Cabo Rojo Municipio, PR 11 km (7 mi) SW earthquakes near Cabo Rojo Municipio
Lajas Municipio, PR 11 km (7 mi) SE earthquakes near Lajas Municipio
Sabana Grande Municipio, PR 17 km (10 mi) E earthquakes near Sabana Grande Municipio
Maricao Municipio, PR 22 km (13 mi) NE earthquakes near Maricao Municipio

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

Aftershocks so far

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

  1. 2.8 2 km SW of Fuig, Puerto Rico
  2. 1.8 3 km W of Guánica, Puerto Rico
  3. 1.8 Puerto Rico region
  4. 2.3 1 km S of Guayanilla, Puerto Rico
  5. 2.5 7 km SE of Maria Antonia, Puerto Rico
  6. 2.5 Puerto Rico region
  7. 2.5 4 km SW of La Parguera, Puerto Rico
  8. 1.7 6 km WSW of Fuig, Puerto Rico
  9. 2.8 1 km ESE of Indios, Puerto Rico
  10. 2.3 2 km WSW of Indios, Puerto Rico
  11. 2.7 7 km SSW of Guánica, Puerto Rico
  12. 3.0 9 km SSW of Guánica, Puerto Rico
  13. 2.3 1 km ENE of Indios, Puerto Rico
  14. 2.1 1 km WSW of Guayanilla, Puerto Rico
  15. 2.6 2 km WSW of Guayanilla, 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.