QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8ml

Earthquake near Saint George, UT

No earthquake was likely felt in Saint George in the 24 hours to 2:37 am MST (09:37 UTC). The last one was M 4.0, 95 km (59 mi) W, at 1:16 am MDT on 6 June 2025, estimated intensity II (weak) in town; 37 felt reports to USGS. Every earthquake near Saint George

This page: a magnitude 3.8 earthquake was recorded 44 km (28 mi) north of Saint George, UT, at 3:44 am MDT on 21 July 2020 (09:44 UTC), 8.7 km deep. 52 people have reported feeling it to USGS.

USGS: 11 km N of Pine Valley, Utah

47 km (29 mi) N of St. George, UT

3:44 am MDT, Jul 21, 2020 · · 8.7 km deep · released about 7.3 tons of TNT

Every earthquake near Saint George Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Washington County 26 kmIron County 49 kmBeaver County 98 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
3:44 am MDT on 21 July 2020 ()
Where
44 km (28 mi) north of Saint George, UT · earthquakes near Saint George
Magnitude
M 3.8 (ml)
Depth
8.7 km below the surface
Felt
52 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Nearest
Washington County, 26 km S
Nearest mapped fault
Hurricane fault, 24 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2071 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 82 km (51 mi) from the epicentre. In Saint George, 44 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.

Likely felt in: Enterprise 22 km, intensity III · Hurricane 40 km, intensity II · Cedar City 43 km, intensity II · Saint George 44 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.3 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.

  1. Northridge, California 1994 M 6.7 23,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 730× the energy of this one
  4. This earthquake M 3.8 about 7.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 15× 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 4.2 on 2016-01-15 — about 4.7 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 6.3 Near Pine Valley, Utah · 11 km S of this epicentre
  2. 5.9 3 km SSE of Washington, Utah · 44 km S 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 37.4948, -113.4887. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Washington County, UT 26 km (16 mi) S earthquakes near Washington County
Iron County, UT 49 km (30 mi) NNE earthquakes near Iron County
Beaver County, UT 98 km (61 mi) NNE earthquakes near Beaver County

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

Aftershocks so far

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

  1. 1.7 12 km WNW of Kanarraville, Utah
  2. 1.8 12 km N of New Harmony, Utah
  3. 1.6 12 km N of New Harmony, Utah
  4. 2.0 12 km WNW of Kanarraville, Utah
  5. 1.5 12 km WNW of Kanarraville, Utah
  6. 2.0 4 km WNW of Washington, Utah
  7. 1.5 15 km SE of Kanarraville, Utah
  8. 2.7 10 km N of Springdale, Utah
  9. 1.5 11 km WSW of Veyo, Utah
  10. 1.7 18 km WNW of Cedar City, Utah
  11. 1.5 14 km SE of Kanarraville, Utah
  12. 1.5 12 km N of Pine Valley, Utah
  13. 1.7 32 km NNE of Newcastle, Utah
  14. 1.8 8 km NW of Cedar City, Utah
  15. 1.7 13 km SSE of Kanarraville, Utah

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.