Earthquake · reviewed by a seismologist
M 3.5md
78 km N of Culebra, Puerto Rico
Yes. A magnitude 3.5 earthquake was recorded 78 km N of Culebra, Puerto Rico, at 10:55 pm AST on 22 September 2021 (02:55 UTC), 65 km deep.
- When
- Magnitude
- M 3.5 (md)
- Depth
- 65 km below the surface
- Felt
- no reports yet
- Nearest
- Culebra Municipio, 76 km S
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1876 days ago
Earthquake alerts for Culebra, PR
Get a notification in this browser when USGS records an earthquake near Culebra, 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 7 km (4 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 3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 57,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 2,500× the energy of this one
- Magna, Utah 2020 M 5.7 1,800× the energy of this one
- This earthquake M 3.5 about 3 tons of TNT
- Around the size people start to feel M 3.0 this one released 6.2× 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 5.0 on 2021-02-06 — about 150 times the energy of this one.
Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:
- 6.1 91 km N of Charlotte Amalie, U.S. Virgin Islands · 47 km ENE of this epicentre
- 5.1 107 km N of Charlotte Amalie, U.S. Virgin Islands · 46 km NE of this epicentre
- 5.1 122 km NNE of Vieques, Puerto Rico · 45 km N of this epicentre
- 5.0 109 km N of Charlotte Amalie, U.S. Virgin Islands · 43 km NE of this epicentre
- 5.0 73 km NNE of Vieques, Puerto Rico · 26 km W 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 19.0080, -65.2466. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Culebra Municipio, PR | 76 km (47 mi) | S | earthquakes near Culebra Municipio |
| Fajardo Municipio, PR | 78 km (48 mi) | SSW | earthquakes near Fajardo Municipio |
| Luquillo Municipio, PR | 86 km (54 mi) | SW | earthquakes near Luquillo Municipio |
| Río Grande Municipio, PR | 91 km (57 mi) | SW | earthquakes near Río Grande Municipio |
| Ceiba Municipio, PR | 93 km (58 mi) | SSW | earthquakes near Ceiba Municipio |
| Loíza Municipio, PR | 96 km (60 mi) | SW | earthquakes near Loíza Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
44 earthquakes have been recorded within 50 km since this one.
- 3.5 84 km NNE of Luquillo, Puerto Rico
- 3.5 106 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.7 102 km NNW of Charlotte Amalie, U.S. Virgin Islands
- 3.0 66 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.5 74 km N of Culebra, Puerto Rico
- 3.7 75 km N of Charlotte Amalie, U.S. Virgin Islands
- 4.0 66 km N of Culebra, Puerto Rico
- 3.7 67 km N of Culebra, Puerto Rico
- 3.6 Puerto Rico region
- 3.4 86 km N of Culebra, Puerto Rico
- 3.6 63 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 44 km NNW of Charlotte Amalie, U.S. Virgin Islands
- 3.4 75 km NNW of Charlotte Amalie, U.S. Virgin Islands
- 3.5 54 km NNE of Luquillo, Puerto Rico
- 3.4 51 km N of Charlotte Amalie, U.S. Virgin Islands
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.