Earthquake · reviewed by a seismologist
M 3.8md
99 km N of Charlotte Amalie, U.S. Virgin Islands
Yes. A magnitude 3.8 earthquake was recorded 99 km N of Charlotte Amalie, U.S. Virgin Islands, at 10:27 pm AST on 20 October 2020 (02:27 UTC), 79 km deep. 2 people have reported feeling it to USGS.
- When
- Magnitude
- M 3.8 (md)
- Depth
- 79 km below the surface
- Felt
- 2 reports · strongest reported intensity IV
- Nearest
- Culebra Municipio, 113 km SSW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2132 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 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 6.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 27,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 1,200× the energy of this one
- Magna, Utah 2020 M 5.7 840× the energy of this one
- This earthquake M 3.8 about 6.4 tons of TNT
- Around the size people start to feel M 3.0 this one released 13× 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 2019-02-18 — about 38 times the energy of this one.
Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 131 km NNE of Cruz Bay, U.S. Virgin Islands · 43 km NE of this epicentre
- 6.1 91 km N of Charlotte Amalie, U.S. Virgin Islands · 8 km SSW of this epicentre
- 6.0 112 km N of Charlotte Amalie, U.S. Virgin Islands · 19 km NW of this epicentre
- 5.9 68 km N of Cruz Bay, U.S. Virgin Islands · 33 km SSE of this epicentre
- 5.9 65 km NNE of Cruz Bay, U.S. Virgin Islands · 45 km SSE 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 19.2281, -64.8028. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Culebra Municipio, PR | 113 km (71 mi) | SSW | earthquakes near Culebra Municipio |
| Fajardo Municipio, PR | 125 km (78 mi) | SW | earthquakes near Fajardo Municipio |
| Luquillo Municipio, PR | 135 km (84 mi) | SW | earthquakes near Luquillo Municipio |
| Ceiba Municipio, PR | 138 km (86 mi) | SW | earthquakes near Ceiba Municipio |
| Río Grande Municipio, PR | 141 km (88 mi) | SW | earthquakes near Río Grande Municipio |
| Loíza Municipio, PR | 148 km (92 mi) | SW | earthquakes near Loíza Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
42 earthquakes have been recorded within 50 km since this one.
- 3.1 74 km N of Culebra, Puerto Rico
- 3.4 89 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 98 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 102 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.4 79 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.3 96 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.3 94 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 58 km N of Cruz Bay, U.S. Virgin Islands
- 3.4 93 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.4 99 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 97 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.2 108 km N of Cruz Bay, U.S. Virgin Islands
- 3.2 110 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.4 104 km N of Charlotte Amalie, U.S. Virgin Islands
- 3.4 91 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.