Earthquake · reviewed by a seismologist
M 3.9md
56 km WNW of Rincón, Puerto Rico
Yes. A magnitude 3.9 earthquake was recorded 56 km WNW of Rincón, Puerto Rico, at 7:30 pm AST on 27 May 2021 (23:30 UTC), 99 km deep. 5 people have reported feeling it to USGS.
- When
- Magnitude
- M 3.9 (md)
- Depth
- 99 km below the surface
- Felt
- 5 reports · strongest reported intensity III
- Nearest
- Mayagüez Municipio, 52 km SSW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1929 days ago
Earthquake alerts for Rincón, PR
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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 it was probably too small to be felt, even directly above it. 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 15,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 680× the energy of this one
- Magna, Utah 2020 M 5.7 480× the energy of this one
- This earthquake M 3.9 about 11 tons of TNT
- Around the size people start to feel M 3.0 this one released 23× 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 4.6 on 2020-01-29 — about 11 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 6.4 32 km NW of Aguadilla, Puerto Rico · 39 km ENE of this epicentre
- 6.3 58 km E of Punta Cana, Dominican Republic · 13 km WSW of this epicentre
- 5.8 33 km NW of San Antonio, Puerto Rico · 49 km ENE 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 18.5296, -67.7435. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mayagüez Municipio, PR | 52 km (32 mi) | SSW | earthquakes near Mayagüez Municipio |
| Rincón Municipio, PR | 56 km (35 mi) | ESE | earthquakes near Rincón Municipio |
| Aguada Municipio, PR | 61 km (38 mi) | ESE | earthquakes near Aguada Municipio |
| Aguadilla Municipio, PR | 63 km (39 mi) | E | earthquakes near Aguadilla Municipio |
| Añasco Municipio, PR | 70 km (43 mi) | ESE | earthquakes near Añasco Municipio |
| Moca Municipio, PR | 72 km (45 mi) | ESE | earthquakes near Moca Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
32 earthquakes have been recorded within 50 km since this one.
- 2.6 35 km WSW of Stella, Puerto Rico
- 3.4 59 km NW of San Antonio, Puerto Rico
- 3.4 63 km W of Rincón, Puerto Rico
- 3.1 45 km NW of Aguadilla, Puerto Rico
- 3.6 59 km W of Rincón, Puerto Rico
- 3.6 57 km NE of Punta Cana, Dominican Republic
- 3.3 46 km WSW of Stella, Puerto Rico
- 3.2 29 km NNW of Rincón, Puerto Rico
- 3.4 50 km ESE of Punta Cana, Dominican Republic
- 3.2 49 km W of Rincón, Puerto Rico
- 3.2 48 km NW of San Antonio, Puerto Rico
- 3.2 37 km NW of San Antonio, Puerto Rico
- 3.3 44 km ENE of Punta Cana, Dominican Republic
- 2.7 26 km NW of Rincón, Puerto Rico
- 3.1 68 km NW of San Antonio, 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.