QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3ml

Earthquake near Logan, UT

No earthquake was likely felt in Logan in the 24 hours to 9:19 am MST (16:19 UTC). The last one was M 2.6, 16 km (10 mi) ESE, at 6:52 am MDT on 25 June 2026, estimated intensity II (weak) in town; 19 felt reports to USGS. Every earthquake near Logan

This page: a magnitude 2.3 earthquake was recorded 30 km (19 mi) east-northeast of Logan, UT, at 7:43 pm MDT on 20 August 2021 (01:43 UTC), 6.5 km deep.

USGS: 10 km WSW of Garden, Utah

31 km (19 mi) ENE of Logan, UT · 125 km (77 mi) NNE of Salt Lake City, UT

7:43 pm MDT, Aug 20, 2021 · · 6.5 km deep · released about 91 lb of TNT

Every earthquake near Logan Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cache County 24 kmRich County 33 kmFranklin County 45 kmBear Lake County 50 kmWeber County 72 kmLincoln County 80 kmMorgan County 85 kmOneida County 92 kmUinta County 101 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
7:43 pm MDT on 20 August 2021 ()
Where
30 km (19 mi) east-northeast of Logan, UT · earthquakes near Logan
Magnitude
M 2.3 (ml)
Depth
6.5 km below the surface
Felt
no reports yet
Nearest
Cache County, 24 km WSW
Nearest mapped fault
Western Bear Lake fault, 16 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 1908 days ago

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 19 km (12 mi) from the epicentre. In Logan, 30 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: North Logan, Hyde Park, Richmond, Smithfield.

How big was it?

This earthquake released about 91 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 170,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 120,000× the energy of this one
  3. Around the size people start to feel M 3.0 10× the energy of this one
  4. This earthquake M 2.3 about 91 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 4 earthquakes of M5 or more within 50 km:

  1. 5.8 8 km W of Garden City, Utah · 10 km N of this epicentre
  2. 5.5 26 km E of Avon, Utah · 39 km S of this epicentre
  3. 5.2 16 km ENE of North Logan, Utah · 11 km WSW of this epicentre
  4. 5.0 2 km S of Richmond, Utah · 27 km WNW 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 41.8507, -111.5010. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cache County, UT 24 km (15 mi) WSW earthquakes near Cache County
Rich County, UT 33 km (20 mi) SE earthquakes near Rich County
Franklin County, ID 45 km (28 mi) NW earthquakes near Franklin County
Bear Lake County, ID 50 km (31 mi) NNE earthquakes near Bear Lake County
Weber County, UT 72 km (45 mi) SSW earthquakes near Weber County
Lincoln County, WY 80 km (49 mi) ENE earthquakes near Lincoln County

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

Aftershocks so far

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

  1. 1.6 7 km ESE of North Logan, Utah
  2. 1.7 Utah
  3. 2.5 2 km NNW of Benson, Utah
  4. 3.2 1 km NE of Benson, Utah
  5. 1.9 Utah
  6. 2.7 1 km NNE of Benson, Utah
  7. 1.8 1 km NNE of Benson, Utah
  8. 1.9 3 km NNW of Benson, Utah
  9. 2.8 2 km N of Benson, Utah
  10. 2.0 0 km ENE of Benson, Utah
  11. 2.6 2 km NW of Benson, Utah
  12. 2.5 2 km NNE of Benson, Utah
  13. 2.3 0 km NW of Benson, Utah
  14. 2.6 3 km SSE of Trenton, Utah
  15. 1.6 3 km NW of Amalga, 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.