4 Things to Know About the Wasatch Fault

So, you decided to come to the University of Utah. Welcome to the U! It’s a great place to be most of the time. Its location on the edge of Salt Lake City offers great access to downtown life with the mountains essentially in your backyard! I remember feeling excited but very overwhelmed when I first arrived. Oh, and incredibly out of my depth. It didn’t help when I realized just how much I didn’t know about the area where I was about to live. The moment I most felt this was when I realized that, as well as being on the edge of the mountains and the city, the campus was also located directly on top of an active fault.

Sure, my experience is probably quite a bit different than many people that come to the U, as I’m sure most people here are at least aware of the possibility of an earthquake in Salt Lake City. Still, with how much of an impact this natural hazard poses on the valley, I’m surprised that it isn’t mentioned more often. As such, here are a few things I think you should know about living on top of the Wasatch Fault.


1. The area is rifting

One of the reasons why I was most confused about an earthquake occurring in Utah was because I wasn’t sure what could cause one. Utah isn’t on the edge of a plate boundary, and it isn’t located over a hot spot like Hawaii is. Why is the area prone to earthquakes, then? As it turns out, Utah may not be on the edge of a tectonic plate, but it is experiencing tectonic stresses that are causing the crust to extend, or rift. As the crust stretches, rocks are forced to move and break, producing the earthquakes that can be found in the area.


2. The Wasatch Fault is a normal fault

As far as naming goes, “normal” doesn’t do much to give any clues to describe movement along a fault. In any case, the Wasatch Fault is classified as a normal fault, which just means that the rock on top of the fault slides down relative the rock beneath it. This is typical behavior for faults in areas undergoing extension. It is also the reason why the valley has such magnificent mountains on both sides. With each earthquake, the mountains get relatively higher and the valley relatively lower.


3. The Wasatch Fault is segmented

The Wasatch Fault is incredibly long; at around 213 miles, it is one of the longest normal faults in North America. This is far too much distance for the ground to rupture all at once (rocks just can’t store enough energy for this to happen), so the fault is broken up into ten segments that each rupture at separate times. This isn’t to say that the segments aren’t connected. It is possible that an earthquake on one section of the fault could trigger another one on a different segment. This, however, does not necessarily have to happen, and means that an event at one place on the fault does not spell disaster for the entirety of Utah.


4. The segments vary in nature

Thanks to the segmented nature of the fault, each section has its own characteristics. Some are able to maintain more strain before rupturing, which produces less frequent but larger earthquakes. Due to this, it is hard to predict when the next large event will occur. On average, surface rupture (produced by large earthquakes) has been found to occur around every 350 years. This does not mean, however, to expect a disaster every 350 years. This average value smooths out a lot of data of variable intervals between events, producing a lot of uncertainty as to when to expect the next big quake.

Though it’s important to understand the potential for a natural disaster occurring in Salt Lake City, it really can be a great place to live. Just keep an emergency kit with food and water around and make sure that you stabilize loose furniture as much as possible. Make sure you’re prepared for a large earthquake, but don’t let it run your life. After all, every place has its own unique hazards. Might as well live in a place that can shake things up a bit.


Images: Cover, 1, 2, 3, 4