QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4md

Earthquake near Pole Ojea, PR

No earthquake was likely felt in Pole Ojea in the 24 hours to 7:51 pm AST (23:51 UTC). The last one was M 2.1, 8 km (5 mi) ENE, at 11:57 pm AST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Pole Ojea

This page: a magnitude 3.4 earthquake was recorded 7 km (4 mi) east-southeast of Pole Ojea, PR, at 8:46 pm AST on 12 August 2021 (00:46 UTC), 9.0 km deep. 3 people have reported feeling it to USGS.

USGS: 6 km ESE of Pole Ojea, Puerto Rico

27 km (17 mi) S of Mayagüez, PR · 123 km (76 mi) WSW of San Juan, PR

8:46 pm AST, Aug 12, 2021 · · 9.0 km deep · released about 1.7 tons of TNT

Every earthquake near Pole Ojea Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cabo Rojo Municipio 8 kmLajas Municipio 9 kmSan Germán Municipio 19 kmHormigueros Municipio 20 kmGuánica Municipio 21 kmSabana Grande Municipio 24 kmMaricao Municipio 31 kmYauco Municipio 32 kmLas Marías Municipio 34 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
8:46 pm AST on 12 August 2021 ()
Where
7 km (4 mi) east-southeast of Pole Ojea, PR · earthquakes near Pole Ojea
Magnitude
M 3.4 (md)
Depth
9.0 km below the surface
Felt
3 reports · strongest reported intensity III
Nearest
Cabo Rojo Municipio, 8 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1839 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 55 km (34 mi) from the epicentre. In Pole Ojea, 7 km away, the estimate is intensity III (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: Pole Ojea 7 km, intensity III · Puerto Real 15 km, intensity III · San Germán 16 km, intensity III · Mayagüez 27 km, intensity II · Yauco 30 km, intensity II · Guayanilla 36 km, intensity II · Magas Arriba 38 km, intensity II · Tallaboa 43 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 100,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,200× the energy of this one
  4. This earthquake M 3.4 about 1.7 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3.5× 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 6.4 on 2020-01-07 — about 36,000 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.8 4 km E of Moca, Puerto Rico · 50 km N of this epicentre
  2. 5.2 19 km SW of Stella, Puerto Rico · 37 km NW of this epicentre
  3. 5.1 21 km SW of Stella, Puerto Rico · 36 km NW 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 17.9551, -67.1241. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cabo Rojo Municipio, PR 8 km (5 mi) NW earthquakes near Cabo Rojo Municipio
Lajas Municipio, PR 9 km (6 mi) ENE earthquakes near Lajas Municipio
San Germán Municipio, PR 19 km (12 mi) NNE earthquakes near San Germán Municipio
Hormigueros Municipio, PR 20 km (12 mi) N earthquakes near Hormigueros Municipio
Guánica Municipio, PR 21 km (13 mi) E earthquakes near Guánica Municipio
Sabana Grande Municipio, PR 24 km (15 mi) NE earthquakes near Sabana Grande Municipio

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

Aftershocks so far

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

  1. 2.7 11 km SSW of Guánica, Puerto Rico
  2. 2.5 3 km WSW of Guánica, Puerto Rico
  3. 2.8 4 km SSW of Guánica, Puerto Rico
  4. 2.7 1 km NNE of Indios, Puerto Rico
  5. 2.4 6 km WSW of La Parguera, Puerto Rico
  6. 3.1 5 km SW of Guánica, Puerto Rico
  7. 2.5 2 km WNW of Indios, Puerto Rico
  8. 2.6 2 km W of Guayanilla, Puerto Rico
  9. 2.3 7 km SE of Maria Antonia, Puerto Rico
  10. 2.5 9 km SSE of Maria Antonia, Puerto Rico
  11. 2.5 5 km SE of Maria Antonia, Puerto Rico
  12. 3.0 9 km SE of Maria Antonia, Puerto Rico
  13. 3.0 4 km SE of Indios, Puerto Rico
  14. 2.1 6 km SW of La Parguera, Puerto Rico
  15. 2.2 7 km SW of La Parguera, 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.