QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Earthquake near Saint George, UT

USGS: 24 km ESE of Littlefield, Arizona

30 km (19 mi) SSW of St. George, UT

8:19 am MDT, Aug 21, 2016 · · 3.7 km deep · released about 41 lb of TNT

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10 km30 km60 km120 km N Washington County 52 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
8:19 am MDT on 21 August 2016 ()
Where
33 km (20 mi) SSW of Saint George, UT · earthquakes near Saint George
Magnitude
M 2.1 (ml)
Depth
3.7 km below the surface
Felt
no reports yet
Nearest
Washington County, 52 km NNE
Nearest mapped fault
Washington fault, 8 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 3014 days ago

A magnitude 2.1 earthquake was recorded 33 km (20 mi) SSW of Saint George, UT, at 8:19 am MDT on 21 August 2016 (14:19 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Beaver Dam.

How big was it?

This earthquake released about 41 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.

  1. Mineral, Virginia 2011 M 5.8 370,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 260,000× the energy of this one
  3. Around the size people start to feel M 3.0 23× the energy of this one
  4. This earthquake M 2.1 about 41 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 lists one earthquake of M5 or more within 50 km:

  1. 5.9 3 km SSE of Washington, Utah · 35 km NNE 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 36.8152, -113.6642. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Washington County, UT 52 km (32 mi) NNE earthquakes near Washington County
Lincoln County, NV 140 km (87 mi) NW earthquakes near Lincoln County

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

Aftershocks so far

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

  1. 1.6 34 km S of Saint George, Utah
  2. 1.6 17 km SSE of Saint George, Utah
  3. 1.6 16 km SSE of Saint George, Utah
  4. 2.2 20 km NNW of Mesquite, Nevada
  5. 1.6 17 km SSE of Saint George, Utah
  6. 1.5 17 km SSE of Saint George, Utah
  7. 1.8 17 km SSE of Saint George, Utah
  8. 3.0 18 km SSE of Saint George, Utah
  9. 1.9 17 km SSE of Saint George, Utah
  10. 1.8 Utah
  11. 3.1 19 km SSE of Saint George, Utah
  12. 2.6 17 km SSE of Saint George, Utah
  13. 1.8 16 km SSE of Saint George, Utah
  14. 2.3 2 km NNE of Beaver Dam, Arizona
  15. 1.7 6 km NNE of Beaver Dam, Arizona

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.