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4.2 quake shakes Magna

Photo University of Utah Seismograph Stations

MAGNA, Utah — The USGS reports a 4.2 magnitude aftershock just north of Magna.

This is the second 4.2 magnitude aftershock that rocked the Salt Lake valley in as many days and comes almost a month after a 5.7 magnitude earthquake caused millions in damage.  More than 1200 aftershocks have hit the Salt Lake Valley since the initial quake.

The USGS reports Thursday’s earthquake was centered just a few miles northeast of Magna.


But what do scientists know about this area?  Not a lot it turns out.

Katherine Whidden, research Scientist with the University of Utah Seismology department says they are using what she terms “this earthquake sequence” to map the underground fault structure.

Whidden says “the main fault line along the Wasatch Front is similar to a tree trunk.  Everyone can see it and we know a lot about it.”  But, like a tree, the main fault has many branches, which in turn have more branches.

Seismologists are trying to determine if the Magna quake comes from the main branch or a smaller one.  They also want to know if this quake created a brand new line or it’s always been here, just dormant for a very long time.

But, Whidden says, “this is a Normal Fault, where one side drops down relative to the other.”

It’s unlike a Thrust Fault where one side moves up and over the other.  “That’s the most devastating kind like we see in Alaska or South America” says Whidden.

Seismologists say that it is not uncommon for aftershocks to continue for weeks or even months after an earthquake.

For a list of the most recent earthquakes, check our earthquake tracker.

The latest aftershock comes the same day as the Great Utah Shakeout where millions across the world practice earthquake safety and drop, cover and hold on.


Did you feel it? You can report your experience here.

Here’s what the experts say to do during an earthquake. 

Earthquake preparedness and resources

For the latest earthquakes in our region, please visit the KSL earthquake tracker.

Utah is “Earthquake Country,” meaning the state is susceptible to earthquakes, especially along the Wasatch Front. It’s important to prepare yourself and your family for an earthquake. Here are some basic tips on earthquake preparedness:

Before an Earthquake

  • Move or secure objects that could fall and hurt you
  • Identify your building’s potential weaknesses and begin to fix them
  • Create a disaster-preparedness plan and have disaster supply kits ready

During an Earthquake

  • Seek cover under sturdy furniture or doorways. As things move, hold on, and move with it.
  • Move away from windows and objects that could fall
  • Move against a wall in the interior of the building, cover and protect yourself