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Expert weighs in on liquefaction: Byproduct of large earthquakes that could bring big damage to parts of Utah

Posted at 6:59 PM, Feb 25, 2019
and last updated 2019-02-26 08:29:30-05

BLUFFDALE, Utah -- Bluffdale residents felt two small jolts Monday morning, as the number of earthquakes in that area in the past two weeks has grown to just under 140.

The pair of earthquakes registered at magnitudes of 1.3 and 1.2. It was enough for some residents to feel, like Amber Hatton—who made a Costco run later that day to help update her 72-hour kit.

“I could feel my mattress shaking a little bit,” she said. “They were just little ones, but it still kind of gets you thinking, ‘Alright, we need to keep working on all this stuff.’”

While the constant rumbling is bringing safety kits to top-of-mind, another concern bubbling to the surface is called “liquefaction.”

Utah Geological Survey hazards geologist Emily Kleber explained that when an earthquake encounters sandy soil saturated with water, the shaking can agitate it.

That agitation can cause buildings and objects on the surface to crack, crumble or sink while objects underneath the ground can rise to the surface.

She showed maps that outline the areas of the valley with sandy soil. The highest at-risk areas revolve around bodies of water, like the Great Salt Lake, Utah Lake, and the Jordan River.

“It can be particularly dangerous because it's fairly widespread through the valley,” she said.

According to the UGS, smaller earthquakes-- like the ones shaking the Bluffdale area lately-- won’t trigger liquefaction.

“As your magnitude increases, you can have a higher risk of liquefaction,” Kleber said.

She said many people might think of liquefaction as the ground opening up and everything falling in, but Kleber said that’s actually a common misconception.

More likely, liquefaction will cause cracks in driveways, sidewalks, roads, and home foundations. Pipes buried below the ground can resurface, becoming exposed.

In more extreme cases, Kleber said buildings can fall over.

Hatton lives in an area where liquefaction is a concern. She explained how her builder took steps to make her home safer.

“When we were building our house, they brought in extra loads of sand and compacted it, just to make it a little more of a sturdy foundation,” she said.

Click hereto see if your home sits in an area prone to liquefaction.

You can find more information on preparing your home for an earthquake on bereadyutah.gov.