quarry blast · reviewed by a seismologist
M 1.7ml
Earthquake near Ardmore, OK
No earthquake was likely felt in Ardmore in the 24 hours to 5:56 pm CST (23:56 UTC). The last one was M 3.4, 180 km (112 mi) NNW, at 5:53 am CST on 7 November 2026, estimated intensity II (weak) in town; 23 felt reports to USGS. Every earthquake near Ardmore
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.7 quarry blast was recorded 35 km (22 mi) northeast of Ardmore, OK, at 12:15 pm CDT on 24 September 2021 (17:15 UTC), less than 1 km deep.
USGS: 3 km WSW of Mill Creek, Oklahoma
- When
- 12:15 pm CDT on 24 September 2021 ()
- Where
- 35 km (22 mi) northeast of Ardmore, OK · earthquakes near Ardmore
- Oklahoma today
- every earthquake in Oklahoma in the last 24 hours
- Magnitude
- M 1.7 (ml)
- Depth
- 0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Johnston County, 21 km ESE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1871 days ago
Earthquake alerts for Ardmore, OK
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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 11 km (7 mi) from the epicentre. In Ardmore, 35 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: Sulphur, Tishomingo, Dickson, Davis.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 9.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 100× the energy of this one
- This earthquake M 1.7 about 9.3 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 34.3932, -96.8650. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Johnston County, OK | 21 km (13 mi) | ESE | earthquakes near Johnston County |
| Murray County, OK | 22 km (13 mi) | WNW | earthquakes near Murray County |
| Pontotoc County, OK | 40 km (25 mi) | NNE | earthquakes near Pontotoc County |
| Marshall County, OK | 42 km (26 mi) | SSE | earthquakes near Marshall County |
| Carter County, OK | 42 km (26 mi) | WSW | earthquakes near Carter County |
| Garvin County, OK | 54 km (34 mi) | NW | earthquakes near Garvin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
50 earthquakes have been recorded within 50 km since this one.
- 1.5 8 km NNE of Stonewall, Oklahoma
- 1.6 11 km SSE of Wapanucka, Oklahoma
- 1.5 7 km N of Mill Creek, Oklahoma
- 1.5 3 km WSW of Mill Creek, Oklahoma
- 1.5 9 km ESE of Ada, Oklahoma
- 1.9 6 km SW of Ada, Oklahoma
- 2.1 8 km SSW of Wynnewood, Oklahoma
- 2.0 8 km SSW of Wynnewood, Oklahoma
- 1.5 11 km SE of Katie, Oklahoma
- 1.6 1 km S of Mill Creek, Oklahoma
- 1.9 7 km N of Mill Creek, Oklahoma
- 1.6 3 km WSW of Mill Creek, Oklahoma
- 1.9 5 km SE of Mill Creek, Oklahoma
- 1.5 7 km W of Davis, Oklahoma
- 1.6 2 km S of Mill Creek, Oklahoma
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.