Was the March 18, 2020, Magna Earthquake in the Forecast?

Mackenzie CopeGeology, Recent earthquakes

Utah Geological Survey has a 50-year forecast for earthquakes.

In 2016, the Working Group on Utah Earthquake Probabilities (WGUEP) published a 50-year forecast for moderate to large earthquakes in the Wasatch Front region. They determined there was a 93% chance of having one or more earthquakes of magnitude 5 or larger in that time period. Given that high probability, the March 18, 2020, magnitude 5.7 Magna earthquake was an expected earthquake.

It’s important to understand that the Magna earthquake was not “The Big One” that Utah residents hear about from time to time. The Wasatch Front area has the potential to experience an earthquake larger than magnitude 7, up to a maximum of about magnitude 7.6, which would result in far greater and wide-ranging damage, injuries, and likely deaths. In their 50-year forecast, the WGUEP determined there is a 43% probability, or about a 1-in-2 chance, of having one or more earthquakes of magnitude 6.75 or greater in that time period.

The Magna earthquake should be a reminder that Utahns live in earthquake country, and that there is a reasonable chance that people living in Utah today could experience a large earthquake in their lifetime. As a society, we shouldn’t fear the future, but we should prepare for it.

Mackenzie Cope is a geologist with the Utah Geological Survey.
For more geologic information, visit geology.utah.gov.