Earthquake · reviewed by a seismologist
M 3.3md
53 km N of Brenas, Puerto Rico
Yes. A magnitude 3.3 earthquake was recorded 53 km N of Brenas, Puerto Rico, 66 km (41 mi) NNW of San Juan, PR, at 1:01 am AST on 21 October 2026 (05:01 UTC), 26 km deep.
66 km (41 mi) NNW of San Juan, PR
- When
- Magnitude
- M 3.3 (md)
- Depth
- 26 km below the surface
- Felt
- no reports yet
- Nearest
- Dorado Municipio, 53 km S
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 21 days ago
Earthquake alerts for Brenas, PR
Get a notification in this browser when USGS records an earthquake near Brenas, PR. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 43 km (27 mi) from the epicentre. 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 1.2 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 140,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 6,200× the energy of this one
- Magna, Utah 2020 M 5.7 4,400× the energy of this one
- This earthquake M 3.3 about 1.2 tons of TNT
- Around the size people start to feel M 3.0 this one released 2.5× 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 4.8 on 2017-08-18 — about 200 times the energy of this one.
Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:
- 5.9 78 km N of Arecibo, Puerto Rico · 43 km NW of this epicentre
- 5.7 78 km N of Tierras Nuevas Poniente, Puerto Rico · 35 km NW of this epicentre
- 5.5 64 km N of Tierras Nuevas Poniente, Puerto Rico · 20 km WNW of this epicentre
- 5.1 66 km N of Brenas, Puerto Rico · 14 km NNW of this epicentre
- 5.1 68 km N of Hatillo, Puerto Rico · 48 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 18.9493, -66.3172. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Dorado Municipio, PR | 53 km (33 mi) | S | earthquakes near Dorado Municipio |
| Vega Baja Municipio, PR | 56 km (35 mi) | S | earthquakes near Vega Baja Municipio |
| Toa Baja Municipio, PR | 56 km (35 mi) | SSE | earthquakes near Toa Baja Municipio |
| Vega Alta Municipio, PR | 57 km (35 mi) | S | earthquakes near Vega Alta Municipio |
| Cataño Municipio, PR | 59 km (37 mi) | SSE | earthquakes near Cataño Municipio |
| Barceloneta Municipio, PR | 59 km (37 mi) | SSW | earthquakes near Barceloneta Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
4 earthquakes have been recorded within 50 km since this one.
- 3.0 52 km N of San Juan, Puerto Rico
- 2.5 25 km N of Tierras Nuevas Poniente, Puerto Rico
- 2.8 18 km NNE of Tierras Nuevas Poniente, Puerto Rico
- 3.0 66 km N of San Juan, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.