The United States Geological Survey recorded a Magnitude 5.7 Earthquake at a depth of 11.9 km, about 6 km to the north of the township of Magna in Salt Lake County, Utah, slightly before 7.10 am local time (slightly before 1.10 pm GMT) on Wednesday 18 March 2020. There are no reports of any casualties, but buildings suffered damage across much of the Salt Lake Valley, and significant disruption was caused to electricity, gas, and water supplies due to damaged pipes and cables.
Damage to the Merlin Theatre in Magna, Utah, following a Magnitude 5.7 Earthquake on 18 March 2020. Jeffrey Allred/Deseret News.
The Earthquake occurred on the Intermountain Seismic Belt, a prominent north-south-trending zone of recorded seismicity in the Intermountain West, including the Wasatch Front urban corridor. In northern Utah the Intermountain Seismic Belt forms the transition between east-west-directed stretching in the Basin and Range Province to the west and the more stable crust of the Middle Rocky Mountains to the east. The Intermountain Seismic Belt contains the Wasatch Fault (Utah's most active fault based on geological evidence, though relatively inactive since records began) and many of the state's other most active faults, which commonly show evidence of multiple displacements in the past 10,000 years. Average recurrence intervals for large surface-faulting earthquakes on the most active central segments of the Wasatch fault are 1300-2500 years; recurrence intervals are typically longer (thousands to 10 000 years or more) on other faults in the area.
The approximate location of the 18 March 2020 Utah Earthquake. USGS.
The Basin and Range Province is particularly associated with tilted block faulting, which occurs as areas of the crust are drawn apart by tectonic activity, causing fracturing in the brittle parts of the lithosphere (near-surface rocks), resulting in the formation of a series of blocks, which are then tilted over by further extension, leading to the formation of a series of active faults.
The extent of the Basin and Range Province. USGS.
Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the USGS here.
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