Earthquake · reviewed by a seismologist
M 2.1md
Earthquake near Decatur, AL
No earthquake was likely felt in Decatur in the 24 hours to 11:02 am CST (17:02 UTC). The last one was M 2.5, 14 km (9 mi) NNW, at 10:54 pm CDT on 26 April 2026, estimated intensity III (weak) in town; 2 felt reports to USGS. Every earthquake near Decatur
This page: a magnitude 2.1 earthquake was recorded 29 km (18 mi) west-northwest of Decatur, AL, at 8:49 pm CST on 3 December 2020 (02:49 UTC), 7.0 km deep. 1 person has reported feeling it to USGS.
USGS: 3 km NE of Courtland, Alabama
55 km (34 mi) W of Huntsville, AL · 30 km (18 mi) WNW of Decatur, AL
- When
- 8:49 pm CST on 3 December 2020 ()
- Where
- 29 km (18 mi) west-northwest of Decatur, AL · earthquakes near Decatur
- Magnitude
- M 2.1 (md)
- Depth
- 7.0 km below the surface
- Felt
- 1 report · strongest reported intensity II
- Nearest
- Lawrence County, 18 km SSW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2098 days ago
Earthquake alerts for Decatur, AL
Get a notification in this browser when USGS records an earthquake near Decatur, AL. 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 minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 28 km (17 mi) from the epicentre. In Decatur, 29 km away, the estimate is intensity II (weak). 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.
Earthquakes near other towns within 30 km: Town Creek, Rogersville, Trinity, Moulton.
How big was it?
This earthquake released about 44 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 340,000× the energy of this one
- Magna, Utah 2020 M 5.7 240,000× the energy of this one
- Around the size people start to feel M 3.0 22× the energy of this one
- This earthquake M 2.1 about 44 lb of TNT
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
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.
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 34.6918, -87.2803. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lawrence County, AL | 18 km (11 mi) | SSW | earthquakes near Lawrence County |
| Limestone County, AL | 30 km (19 mi) | ENE | earthquakes near Limestone County |
| Lauderdale County, AL | 41 km (26 mi) | NW | earthquakes near Lauderdale County |
| Colbert County, AL | 48 km (30 mi) | W | earthquakes near Colbert County |
| Morgan County, AL | 48 km (30 mi) | ESE | earthquakes near Morgan County |
| Franklin County, AL | 59 km (36 mi) | WSW | earthquakes near Franklin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
2 earthquakes have been recorded within 50 km since this one.
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.