Tag Archive for: Liquefaction

Not only does Utah’s geology make for stunning landscapes, the textures are pretty great too!

Paria Plateau, Kane County, Utah
Photographer: Tyler Knudsen; © 2013

Liquefaction features in Navajo Sandstone, Paria Plateau, Kane County.

Liquefaction

Liquefaction may occur when water-saturated sandy soils are subjected to earthquake ground shaking. When soil liquefies, it loses strength and behaves as a viscous liquid (like quicksand) rather than as a solid. This can cause buildings to sink into the ground or tilt, empty buried tanks to rise to the ground surface, slope failures, nearly level ground to shift laterally tens of feet (lateral spreading), surface subsidence, ground cracking, and sand blows.




Why is liquefaction a concern?

Liquefaction has caused significant property damage in many earthquakes around the world, and is a major hazard associated with earthquakes in Utah. The 1934 Hansel Valley and 1962 Cache Valley earthquakes caused liquefaction, and large prehistoric lateral spreads exist at many locations along the Wasatch Front. The valleys of the Wasatch Front are especially vulnerable to liquefaction because of susceptible soils, shallow groundwater, and a relatively high probability of moderate to large earthquakes.

Where is liquefaction likely to occur?

A close-up segment of the Liquefaction Susceptibility Map of the Magna quadrangle, Salt Lake County. The colors of the map indicate the level of susceptibility to liquefaction. (From Special Study 137 plate 1)

A close-up segment of the Liquefaction Susceptibility Map of the Magna quadrangle, Salt Lake County. The colors of the map indicate the level of susceptibility to liquefaction. (From Special Study 137 plate 1)

Two conditions must exist for liquefaction to occur:

  1. The soil must be susceptible to liquefaction (loose, water-saturated, sandy soil, typically between 0 and 30 feet below the ground surface).
  2. Ground shaking must be strong enough to cause susceptible soils to liquefy.

Northern, central, and southwestern Utah are the state’s most seismically active areas. Identifying soils susceptible to liquefaction in these areas involves knowledge of the local geology and subsurface soil and water conditions. The most susceptible soils are generally along rivers, streams, and lake shorelines, as well as in some ancient river and lake deposits.

How is liquefaction potential determined?

The liquefaction potential categories shown on liquefaction maps depend on the probability of having an earthquake within a 100-year period that will be strong enough to cause liquefaction in those zones.

  • High liquefaction potential means that there is a 50% probability of having an earthquake within a 100-year period that will be strong enough to cause liquefaction.
  • Moderate means that the probability is between 10% and 50%.
  • Low means that the probability is between 5 and 10%.
  • Very low means that the probability is less than 5%.

What can be done?

To determine the liquefaction potential and likelihood of property damage at a site, a site-specific geotechnical investigation by a qualified professional is needed. If a hazard exists, various hazard-reduction techniques are available, such as soil improvement or special foundation design. The cost of site investigations and/or mitigation measures should be balanced with an acceptable risk.


Read More:

Liquefaction in Utah
Public Information Series 100

Liquefaction in the April 15, 2010, M 4.5 Randolph Earthquake
Survey Notes, v. 43 no. 1, 2011

Liquefaction Advisory Group
Geologic Hazards Working Group


Looking for Liquefaction Maps?

The new, interactive Utah Geologic Hazards Portal is the gateway to all hazards mapping in Utah. Find the type, location, and relative susceptibility of active faults, landslides, and other geologic hazards where data is available.



Or View All Hazards Maps

Search by county and hazard type. Liquefaction maps may be found under General Hazards or Liquefaction sections.

This Issue Contains:

  • Land Subsidence and Earth Fissures in Cedar Valley
  • Updated Landslide Maps of Utah
  • GPS Monitoring of Slow-Moving Landslides
  • Liquefaction in the April 15, 2010, M 4.5 Randolph Earthquake
  • Glad You Asked: What are the Roots of Geobotany?
  • Teacher’s Corner
  • GeoSights: Devils Kitchen, Juab County, Utah
  • Survey News
  • Energy News: Energy Office in Transition
  • New Publications

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Tag Archive for: Liquefaction

Not only does Utah’s geology make for stunning landscapes, the textures are pretty great too!

Paria Plateau, Kane County, Utah
Photographer: Tyler Knudsen; © 2013

Liquefaction features in Navajo Sandstone, Paria Plateau, Kane County.