QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Tremonton, UT

No earthquake was likely felt in Tremonton in the 24 hours to 6:54 pm MST (01:54 UTC). The last one was M 4.7, 140 km (87 mi) SE, at 7:49 am MST on 22 January 2026, estimated intensity II (weak) in town; 4,305 felt reports to USGS. Every earthquake near Tremonton

This page: a magnitude 1.6 earthquake was recorded 41 km (25 mi) northwest of Tremonton, UT, at 5:30 pm MDT on 28 September 2020 (23:30 UTC), less than 1 km deep.

USGS: 12 km ESE of Snowville, Utah

5:30 pm MDT, Sep 28, 2020 · · -0.1 km deep · released about 6.4 lb of TNT

Every earthquake near Tremonton Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Oneida County 30 kmBox Elder County 52 kmFranklin County 68 kmCache County 72 kmPower County 89 kmBannock County 91 kmWeber County 93 kmCassia County 96 kmDavis County 103 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
5:30 pm MDT on 28 September 2020 ()
Where
41 km (25 mi) northwest of Tremonton, UT · earthquakes near Tremonton
Magnitude
M 1.6 (md)
Depth
-0.1 km below the surface
Felt
no reports yet
Nearest
Oneida County, 30 km N
Nearest mapped fault
North Promontory fault, 3 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 2234 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 11 km (7 mi) from the epicentre. In Tremonton, 41 km away, the estimate is intensity I (not felt). 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.

How big was it?

This earthquake released about 6.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.6 about 6.4 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 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 The 1934 Hansel Valley, Utah Earthquake · 34 km SSW of this epicentre
  2. 6.1 17 km NE of Snowville, Utah · 16 km N of this epicentre
  3. 5.9 35 km SSW of Howell, Utah · 44 km SSW of this epicentre
  4. 5.6 Hansel Valley, Utah · 17 km SW of this epicentre
  5. 5.2 27 km SW of Thatcher, Utah · 47 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 41.9190, -112.5747. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Oneida County, ID 30 km (19 mi) N earthquakes near Oneida County
Box Elder County, UT 52 km (32 mi) SW earthquakes near Box Elder County
Franklin County, ID 68 km (42 mi) ENE earthquakes near Franklin County
Cache County, UT 72 km (45 mi) ESE earthquakes near Cache County
Power County, ID 89 km (55 mi) NNW earthquakes near Power County
Bannock County, ID 91 km (56 mi) NNE earthquakes near Bannock County

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

Aftershocks so far

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

  1. 1.6 Utah
  2. 1.9 5 km W of Garland, Utah
  3. 1.5 10 km SSW of Malad City, Idaho
  4. 2.1 2 km SSW of Howell, Utah
  5. 1.7 9 km E of Snowville, Utah
  6. 1.6 14 km WNW of Howell, Utah
  7. 1.7 24 km SSW of Snowville, Utah
  8. 2.0 19 km S of Snowville, Utah
  9. 1.6 12 km NNE of Howell, Utah
  10. 2.0 17 km WSW of Howell, Utah
  11. 2.1 19 km W of Portage, Utah
  12. 2.2 8 km SSW of Portage, Utah
  13. 1.5 18 km NNW of Snowville, Utah
  14. 2.3 34 km WSW of Howell, Utah
  15. 1.7 5 km E of Howell, 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.