JULY 9, 2019

In response to the July 4 and July 5 Ridgecrest, CA earthquakes:

What would happen if there was a magnitude 7.1 earthquake in the Wasatch Front region?

A 2015 scenario was run for the social and economic impacts of a magnitude 7.0 earthquake on the Salt Lake City segment of the Wasatch fault zone:

  • Vulnerable buildings – Brick houses and buildings built 40+ years ago are not made to be stable in earthquake shaking. There are more than 147,000 brick buildings in Salt Lake County that would be vulnerable to significant damage or collapse.
  • Injuries and fatalities – 2,000 – 2,500 fatalities; 7,400 – 9,300 life-threatening injuries.
  • Displaced families – 84,000 families would be displaced from their homes.
  • Disruption of lifelines – Water, electricity, gas, and sewer utilities would be impacted or unavailable for days to months following an earthquake.
  • Economic impact – The 2015 scenario reports an economic loss of over $33 billion, but the losses by 2019 standards would be more than $52 billion.
  • Aftershocks – Aftershocks would continue to occur for days, weeks, or even months after the mainshock. Earthquake shaking would be felt and could further damage already weakened infrastructure and buildings, as well as be unsettling to those who survived the mainshock.

What are the chances of having a magnitude 7.1 earthquake in the Wasatch Front region?

According to a 2016 report and fact sheet by the Working Group on Utah Earthquake Probabilities (WGUEP), there is a greater than a one-in-two chance of a magnitude 6.0 or larger earthquake in less than 50 years.

Helpful Resources

Social Media Accounts 

  • Utah Seismic Safety Commission Twitter – @UtahSeismic
  • University of Utah Seismograph Stations Twitter, most recent earthquakes – @UUSSquake
  • Utah Division of Emergency Management Twitter – @UtahEmergency