Soil Composition

The Geological unit found surrounding our site are:

Qa - alluvial valley deposits from the Pleistocene/Holocene Era that date as old as 11,700 years.  According to the USGS definition, an alluvial valley deposit consists of “well stratified alluvium (gravel, sand, silt, and clay) that accumulate on the floors of axial valleys (Alluvial Deposits)”. This sediment covers the majority of the Mojave desert.

Qc - clay sediment surrounding the dry Lucerne Lake. This can be a result of having an adjacent reservoir(original state) located near any area. We can assume that our site is not on Clay sediments as it is not near any lakes.

The units found on Lucerne Valley suggest that sediments come from Pleistocene or Recent Era.

 

Seismic

The area of interest is not sitting on any active fault lines. The closet fault zone is the Helendale-South Lockhart fault zone located approximately six miles southwest of the site. The next closest zone is the Lewood-Lockhard fault zone located approximately eight miles northeast of the site. Not too many earthquakes have occurred recently near the project site. The nearest earthquake was approximately 16 miles South of the site in Yucaipa with magnitude of 1.42. The second closest earthquake occurred approximately 17 miles southeast of our site in Yucca Valley with a magnitude of 1.35.

 

Flooding

Lucerne Valley is under zone D, according to FEMA areas under zone D have possible but undetermined flood hazards, as no analysis of flood hazards has been conducted. It is also designated for when community incorporates portions of another community’s area where no map was prepared. Zone D flooding insurance rates can be higher than standard as flooding uncertainty is of concern.

 

Liquefaction

Areas of high earthquake concentration, such as the project site area, susceptibility to liquefaction increases. The project site has been considered to have a moderate to high susceptibility to liquefaction based on the water depth and the age of the alluvial deposits at the site. The initial study indicates that the liquefaction susceptibility is moderate to high but soil tests may be needed in order to confirm the conclusion.

 

Landslide

The difference between the highest elevation and the lowest elevation is about 13ft. The max slope is around 10±1% while the average slope ranges from 0-3% slope. The closest mountain is located 0.55 miles away and is 3,208 ft tall. Based on this information the landslide hazard risk level is low for the site.

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