Monday, November 5, 2012

Liquefaction Danger: A Part of Davis County History

A part of Davis County history is also its geological past and present.
One of the greatest dangers in Davis County is earthquake danger, with the locked-up Wasatch Fault traversing through the county.
Major earthquakes have struck Davis County in prehistoric times and they will happen again. It is not a matter of if, it is a matter of when.
Since the Wasatch Fault appears locked tight, is it storing energy for a future quake?
The Utah Geological Survey produced a map in 1994 (and still in use) that highlights the liquefaction dangers during an earthquake for various parts of the state, including Davis County (see a reproduction of the map below).
liquefaction is a "bowl of Jello effect" that could turn some of the ground to a slushy state and cause buildings to sink into the ground and in general cause a much higher destruction rate than from just ground shaking alone.
In Davis County, the map shows that most of Hill Air Force Base, as well as areas east of Highway 89 are in the very low danger range for liquefaction.
In the low area is a section of Davis County that includes the neighborhood where I live, Green Leaf subdivision in Layton, where clay soil dominates.
This low risk area generally goes from about the Hill Field Road Wal-Mart on the south side, to a part of the Layton Hills Mall on the south east and then generally otherwise only those areas west of Main Street on the east side. This area goes north to about Antelope Drive and is just east of the Union Pacific tracks on its western side.
A moderate area surrounds this low risk area and then the rest of the county is pretty much high risk otherwise.
Having earthquake insurance is a pretty wise idea in Davis County, though if you have a brick home, you pay a premium a lot higher than with a frame house.

For more information, go to: http://geology.utah.gov/utahgeo/hazards/liquefy.htm
and http://earthquake.usgs.gov/earthquakes/states/?region=utah




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