2020 Magna Earthquake

Utah experienced a magnitude 5.7 earthquake
on March 18, 2020 at 7:09 a.m.

On the morning of Wednesday, March 18, 2020, northern Utah experienced a magnitude (M) 5.7 earthquake with an epicenter north of Magna, Utah. More than 2,200 aftershocks have occurred since the initial M5.7 earthquake. Additional aftershocks are expected to occur but with decreasing frequency over time. Utah experienced occasional spikes of felt aftershocks of M4 or M3 for weeks afterward.

The count includes:
6 in the magnitude 4 range
34 in the magnitude 3 range
146 in the magnitude 2 range.

Summary on USGS Website

U of U Seismograph Stations Research

New Publication on Magna Earthquake Data

Published September 10, 2020

Plain Language Summary: On 18 March 2020, a moment magnitude (Mw) 5.7 earthquake occurred beneath Magna, Utah, a suburb of Salt Lake City. It was the largest earthquake in the Wasatch fault system in historical times, and shaking was felt throughout northern Utah. The mainshock and its aftershocks were located in the middle of a dense seismic network, generating a rare and valuable data set of strong ground accelerations from normal‐faulting earthquakes. We analyzed the first ~6 weeks of seismic data following the mainshock and found that the aftershocks formed a shallow‐dipping planar structure at depths of 9–12 km, implying that this segment of the Wasatch fault zone has a curved shape. At the surface, it dips steeply to the west at ~70°, but as the depth increases, the dip becomes progressively more shallow. Simulations of ground shaking from large earthquakes previously assumed that this fault segment was planar and steeply dipping (~50°) throughout the upper crust. Our observations suggest that the rupture area of future large earthquakes will be closer to the surface than previously thought, which would cause increased ground shaking in the Salt Lake City metropolitan area with its ~1.2 million residents.

View the Full Publication

Main Quake ShakeMap and Aftershock Timeline

UUSS ShakeMap

Magnitude vs Time

Preliminary Models and Information

This conceptual model illustrates one possible scenario for the location of the M5.7 Magna earthquake and its aftershocks relative to the Wasatch fault and associated faults. The M5.7 earthquake and some of its aftershocks might be on the Wasatch fault or on another nearby fault in the network of faults known as the Wasatch fault system. It is difficult to know for certain which fault or faults these earthquakes occurred on because the locations of these faults at depth are poorly known.

View the U of U Seismograph Stations Website

Example

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President Donald J. Trump Approves Major Disaster Declaration for Utah.

FEMA announced that federal disaster assistance has been made available to the state of Utah to supplement state and local recovery efforts in the areas affected by an earthquake during the period of March 18 to April 17, 2020. The President’s action makes federal funding available to affected individuals in Davis and Salt Lake counties.
The deadline to apply has passed.

Click Here for More Information



If you have earthquake insurance, contact your agent or carrier. However, earthquake damage is not covered by regular homeowners policies. See the Resources section for general financial assistance programs available for historic and unreinforced masonry buildings. 

Geology of the Magna Earthquake

The magnitude 5.7 earthquake and subsequent aftershocks occurred in bedrock. Valley deposits of clay, silt, sand, and gravel in the area are between 200 and 1000 feet thick. The earthquake and aftershocks occurred at depths of about 1 to 8 miles. During the earthquake, the bedrock slid past itself along a crack called a fault. Before the earthquake, friction along the fault kept the bedrock from moving. Then, when stresses in the rock finally built up to overcome the frictional resistance on the fault, the bedrock moved and the stress was released, causing the earthquake. With each break (or rupture) of a fault, the rocks around the earthquake adjust and move in the same fashion; this period of adjustment is shown by the grouping of aftershocks. Analysis is ongoing but there has not been a determination of which fault zone the Magna earthquake occurred on.

Epicenter Map

Epicenter map of earthquakes from the Magna Earthquake Sequence.

U of U Seismograph Stations

3D Model

2020 M5.7 Magna, Utah Earthquake Locations
Updated: July 14, 2020 with 2,317 events

Visit 3D Model of Magna Earthquake

Utah Geological Survey

Utah Geological Survey – Information on the March 18, 2020, Magna Earthquake

Visit the Utah Geological Survey Website

Frequently Asked Questions

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Media

  • Magna Damage in downtown Magna from the Magna Earthquake 2020
  • Magna Roof and shingles damaged from the Magna Earthquake 2020
  • Magna Damage to brick wall in Salt Lake City from the Magna Earthquake 2020
  • Magna Lateral spread geologic features near the Jordan River
  • Magna Damage in downtown Magna from the Magna Earthquake 2020
  • Magna Video of ground shaking from the Magna Earthquake 2020