Earthquake · reviewed by a seismologist
M 3.6mwr
Earthquake near Caldwell, KS
No earthquake was likely felt in Caldwell in the 24 hours to 10:07 am CST (16:07 UTC). The last one was M 3.4, 163 km (101 mi) SSW, at 5:53 am CST on 7 November 2026, estimated intensity II (weak) in town; 23 felt reports to USGS. Every earthquake near Caldwell
This page: a magnitude 3.6 earthquake was recorded 10 km (6 mi) south of Caldwell, KS, at 2:28 pm CDT on 20 April 2018 (19:28 UTC), 5.5 km deep. 13 people have reported feeling it to USGS.
USGS: 3 km ENE of Renfrow, Oklahoma
86 km (54 mi) SSW of Wichita, KS
- When
- 2:28 pm CDT on 20 April 2018 ()
- Where
- 10 km (6 mi) south of Caldwell, KS · earthquakes near Caldwell
- Oklahoma today
- every earthquake in Oklahoma in the last 24 hours
- Magnitude
- M 3.6 (mwr)
- Depth
- 5.5 km below the surface
- Felt
- 13 reports · strongest reported intensity III
- Measured shaking
- intensity IV (ShakeMap)
- USGS impact alert
- green
- Nearest
- Grant County, 23 km SW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3040 days ago
Earthquake alerts for Caldwell, KS
Get a notification in this browser when USGS records an earthquake near Caldwell, KS. 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 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 338 km (210 mi) from the epicentre. In Caldwell, 10 km away, the estimate is intensity IV (light). 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.
Likely felt in: Caldwell 10 km, intensity IV · Blackwell 34 km, intensity III · Wellington 42 km, intensity III · Anthony 43 km, intensity III · Conway Springs 50 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 3.8 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 45,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 2,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400× the energy of this one
- This earthquake M 3.6 about 3.8 tons of TNT
- Around the size people start to feel M 3.0 this one released 7.9× 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 4.3 on 2017-09-08 — about 11 times the energy of this one.
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 36.9451, -97.6185. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Grant County, OK | 23 km (14 mi) | SW | earthquakes near Grant County |
| Sumner County, KS | 34 km (21 mi) | NNE | earthquakes near Sumner County |
| Kay County, OK | 45 km (28 mi) | ESE | earthquakes near Kay County |
| Harper County, KS | 48 km (30 mi) | NW | earthquakes near Harper County |
| Garfield County, OK | 65 km (40 mi) | SSW | earthquakes near Garfield County |
| Alfalfa County, OK | 67 km (42 mi) | WSW | earthquakes near Alfalfa County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 2.5 7 km WSW of Hunnewell, Kansas
- 1.5 8 km ESE of Caldwell, Kansas
- 1.5 8 km WSW of Hunnewell, Kansas
- 3.2 5 km NW of Wellington, Kansas
- 2.5 7 km E of Nescatunga, Oklahoma
- 2.7 7 km E of Nescatunga, Oklahoma
- 2.1 4 km ENE of Milan, Kansas
- 2.6 1 km N of Medford, Oklahoma
- 2.5 7 km E of Bluff City, Kansas
- 1.6 2 km W of Freeport, Kansas
- 2.8 7 km ENE of Nescatunga, Oklahoma
- 2.9 8 km E of Nescatunga, Oklahoma
- 2.9 8 km ENE of Nescatunga, Oklahoma
- 4.4 8 km E of Nescatunga, Oklahoma
- 1.7 5 km SSE of Bluff City, Kansas
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.