Have you ever experienced an earthquake? If you’re like many people living in Utah, you may not think you have. But it’s almost guaranteed that you've lived through one—you just didn’t know it.
You might be surprised to learn that Utah is a seismically active area, with an average of 700 earthquakes (including aftershocks) recorded each year throughout the state. Most of these quakes are small (1-3 on the Richter scale), so they go by unnoticed.
The majority of people living in Utah haven’t experienced a moderate or big quake (4+ on Richter scale), so the threat of a large-scale quake doesn’t seem real. However, Utah has had its share of moderate- to high-magnitude earthquakes.
What are the odds?
Because scientists have been able to determine the pattern of
Are you and your family prepared to survive the damage and disruption caused by a quake?
What actually happens during an earthquake?
You may have learned some basic geology in elementary school—but let’s recap. Most earthquakes happen along faults—the edges of tectonic plates that form the earth’s crust (the outermost layer of the earth). When the edges of these plates bump or slide against each other, it creates energy that radiates from a central point (the hypocenter, or the place below the surface were the plates collide). This energy causes the shaking and ground movement that we recognize as an earthquake. This ground movement can affect the surface in several ways.
Shaking of buildings and objects is the most noticeable effect in an earthquake. This can range from items simply rattling in place to falling off of shelving our out of cabinets and causing additional damage or injury. Landslides, mudslides, and liquefaction can also cause huge amounts of damage to homes, businesses, and community infrastructure (roads, power, sewage, etc.).
Liquefaction is also a problematic effect of earthquakes. Basically, liquefaction means that certain types of soil behave just like liquid during an earthquake. This liquid-land effect can cause some areas to become weak and create an open area that sinks lower than surrounding areas. Liquefaction will especially impact the western parts of Utah’s valley regions because it typically happens in areas where the soil is high in water content and made of various types of sedimentary soil, rather than solid bedrock.
One myth many people fear is that the ground can open up and swallow cars, buildings, and people during an earthquake. This doesn’t happen, but liquefaction can create muddy sinkholes that will engulf cars and cause serious damage to buildings, roadways, and other infrastructure as areas of the surface sink. This sinking can impact the foundations of homes, roadways, and utility lines. Damage to homes can make them uninhabitable, roadways can become blocked or impossible to drive on, and utility lines can break. Ultimately this can cause interruption in or total loss of sewage, gas, electricity, internet and phone services (not to mention potential backing up or flooding of sewage, gas leaks, and downed power lines in your neighborhood).
Where will they happen?
According to the “Putting Down Roots in Earthquake Country” handbook provided by the State of Utah, the Wasatch Fault is 240 miles long and runs through the central part of Utah. It typically falls right along the Wasatch Front—from Malad, ID to Fayette, UT. It is one of the longest and most active faults of its kind in the world.
About half of the damaging earthquakes in Utah since 1850 have occurred along the Wasatch Front. No area of the state is completely free of seismic activity, so everyone should be prepared to survive an earthquake and its damaging effects.
What damage can earthquakes cause?
The University of Utah Seismograph Stations website estimates that a 7.5 magnitude quake could cause significant damage as far as 50 miles away from the center of the quake. If a major earthquake were to happen along the central portion of the Wasatch Front, estimates of the damage to buildings alone reach the billions of dollars, and would impact families and businesses from Davis to Utah counties (and buildings would only make up about 20% of the total damages).
In addition to buildings being damaged, consider the cost of repairing freeways, dams, utility lines and sewage pipes, not to mention the homes, cars, and personal belongings of individual families. The Federal Emergency Management Agency’s (FEMA’s) Hazards US loss-estimation model shows that if Utah experienced a magnitude 7 or greater quake, the following would likely be the result:
- $76 billion in damage and loss to buildings
- 237,000 households (1/5 of the state’s population!) would be displaced because their homes would be too damaged to live in
- 15,700 life-threatening injuries or fatalities
What do you think? Are you ready for a large quake? Have you lived through one already? Let us know what you think in the comments.