Earthquake · reviewed by a seismologist
M 3.6md
100 km NNE of Cruz Bay, U.S. Virgin Islands
Yes. A magnitude 3.6 earthquake was recorded 100 km NNE of Cruz Bay, U.S. Virgin Islands, at 9:33 pm AST on 20 August 2023 (01:33 UTC), 52 km deep. 1 person has reported feeling it to USGS.
- When
- Magnitude
- M 3.6 (md)
- Depth
- 52 km below the surface
- Felt
- 1 report · strongest reported intensity II
- Nearest
- Culebra Municipio, 129 km SW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1110 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 48 km (30 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 4.1 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 42,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 1,900× the energy of this one
- Magna, Utah 2020 M 5.7 1,300× the energy of this one
- This earthquake M 3.6 about 4.1 tons of TNT
- Around the size people start to feel M 3.0 this one released 8.5× 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 5.5 on 2022-05-08 — about 660 times the energy of this one.
Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 131 km NNE of Cruz Bay, U.S. Virgin Islands · 33 km N of this epicentre
- 6.1 91 km N of Charlotte Amalie, U.S. Virgin Islands · 36 km W of this epicentre
- 6.0 112 km N of Charlotte Amalie, U.S. Virgin Islands · 49 km WNW of this epicentre
- 5.9 68 km N of Cruz Bay, U.S. Virgin Islands · 35 km SW of this epicentre
- 5.9 65 km NNE of Cruz Bay, U.S. Virgin Islands · 35 km SSW 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 19.1936, -64.4925. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Culebra Municipio, PR | 129 km (80 mi) | SW | earthquakes near Culebra Municipio |
| Fajardo Municipio, PR | 146 km (91 mi) | SW | earthquakes near Fajardo Municipio |
| Vieques Municipio, PR | 155 km (96 mi) | SW | earthquakes near Vieques Municipio |
| Ceiba Municipio, PR | 158 km (98 mi) | SW | earthquakes near Ceiba Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
49 earthquakes have been recorded within 50 km since this one.
- 3.5 Virgin Islands
- 3.8 90 km NNE of Cruz Bay, U.S. Virgin Islands
- 3.6 104 km NNE of Cruz Bay, U.S. Virgin Islands
- 2.9 141 km NNE of Cruz Bay, U.S. Virgin Islands
- 3.5 103 km NNE of Cruz Bay, U.S. Virgin Islands
- 3.6 Virgin Islands
- 3.8 83 km NNE of Cruz Bay, U.S. Virgin Islands
- 4.2 130 km N of Cruz Bay, U.S. Virgin Islands
- 3.8 90 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.4 108 km N of Cruz Bay, U.S. Virgin Islands
- 3.6 102 km N of Cruz Bay, U.S. Virgin Islands
- 3.7 63 km NNE of Cruz Bay, U.S. Virgin Islands
- 3.4 76 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.7 122 km N of Cruz Bay, U.S. Virgin Islands
- 3.5 62 km N of Cruz Bay, 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.