Could California's levees fail?  NEES@UCLA helps simulate an earthquake to find out.

NEES@UCLA, as part of a team headed by UCLA earthquake experts Scott Brandenberg and Jonathan Stewart, employed state-of-the-art mobile field shakers to simulate an earthquake to test the security of the fragile system of levees in the Sacramento–San Joaquin Delta, the hub of California's water distribution system, which provides fresh water to some 23 million residents throughout the state, including Los Angeles.


Experts have projected that even a moderate earthquake in the 441,000-acre region, which lies on the eastern margin of the San Andreas fault system, could cause multiple levee failures, resulting in major flooding and an influx of saltwater from the San Francisco Bay that would halt water delivery for years, inundate farmland and sensitive wildlife habitat, and cause tens of billions of dollars in damage.


The researchers have constructed a model levee in the delta that measures 6 feet tall and 40 feet wide (see images and video of the construction.) To conduct the full-scale earthquake testing, researchers used the state-of-the-art nees@UCLA Earthquake Engineering Mobile Laboratory, which includes large shakers, actuators, instrumentation and a mobile command center. The test measured the potential deformation of organic foundation soils that could result in a levee breach.


The resulting data on the seismic vulnerability of California's levees could help guide state and federal lawmakers in determining how to best repair and strengthen levees  both those in California, which were built in the mid-19th century, and similar levees around the world.

Steve Keowen, Alberto Salamanca and NEES staff prepare the shaker for testing.