QuakeIndex

Earthquake · reviewed by a seismologist

M 2.7ml

Earthquake near Alva, OK

No earthquake was likely felt in Alva in the 24 hours to 3:39 pm CST (21:39 UTC). The last one was M 3.4, 144 km (90 mi) SSE, at 5:53 am CST on 7 November 2026, estimated intensity II (weak) in town; 23 felt reports to USGS. Every earthquake near Alva

This page: a magnitude 2.7 earthquake was recorded 17 km (11 mi) south-southwest of Alva, OK, at 8:31 am CDT on 18 July 2018 (13:31 UTC), 6.2 km deep. 1 person has reported feeling it to USGS.

USGS: 4 km SE of Avard, Oklahoma

8:31 am CDT, Jul 18, 2018 · · 6.2 km deep · released about 340 lb of TNT

Every earthquake near Alva Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Woods County 11 kmAlfalfa County 40 kmMajor County 44 kmWoodward County 53 kmBarber County 62 kmComanche County 72 kmDewey County 80 kmHarper County 82 kmHarper County 85 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
8:31 am CDT on 18 July 2018 ()
Where
17 km (11 mi) south-southwest of Alva, OK · earthquakes near Alva
Oklahoma today
every earthquake in Oklahoma in the last 24 hours
Magnitude
M 2.7 (ml)
Depth
6.2 km below the surface
Felt
1 report · strongest reported intensity III
Nearest
Woods County, 11 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2960 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 56 km (35 mi) from the epicentre. In Alva, 17 km away, the estimate is intensity III (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.

Likely felt in: Alva 17 km, intensity III · Cherokee 37 km, intensity II · Helena 46 km, intensity II · Mooreland 47 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 340 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 45,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 32,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.8× the energy of this one
  4. This earthquake M 2.7 about 340 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

The largest earthquake within 50 km since 2016 was M 5.1 on 2016-02-13 — about 4,000 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 36.6675, -98.7618. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Woods County, OK 11 km (7 mi) NW earthquakes near Woods County
Alfalfa County, OK 40 km (25 mi) E earthquakes near Alfalfa County
Major County, OK 44 km (27 mi) SSE earthquakes near Major County
Woodward County, OK 53 km (33 mi) WSW earthquakes near Woodward County
Barber County, KS 62 km (39 mi) N earthquakes near Barber County
Comanche County, KS 72 km (45 mi) NW earthquakes near Comanche County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

51 earthquakes have been recorded within 50 km since this one.

  1. 2.2 19 km SSE of Waynoka, Oklahoma
  2. 2.2 6 km ESE of Cleo Springs, Oklahoma
  3. 2.0 5 km ESE of Cleo Springs, Oklahoma
  4. 3.1 5 km ESE of Cleo Springs, Oklahoma
  5. 3.0 16 km SSE of Waynoka, Oklahoma
  6. 3.1 17 km SSE of Waynoka, Oklahoma
  7. 2.9 17 km SSE of Waynoka, Oklahoma
  8. 2.5 17 km SE of Waynoka, Oklahoma
  9. 2.8 8 km SW of Waynoka, Oklahoma
  10. 2.8 17 km SSE of Waynoka, Oklahoma
  11. 2.8 16 km SSE of Waynoka, Oklahoma
  12. 2.7 15 km SSE of Waynoka, Oklahoma
  13. 2.7 5 km WNW of Carmen, Oklahoma
  14. 3.2 15 km SSE of Waynoka, Oklahoma
  15. 2.7 17 km SE of Waynoka, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.