NEES Field and Mobile Laboratories

The ground you stand on may feel solid beneath your feet, but the strong ground motion that occurs during an earthquake can cause the ground to suddenly become unstable and behave like liquid. This change of seemingly solid earth to a loose, shifting soil is called liquefaction. It is not enough to study how to construct earthquake safe structures. Engineers also need to understand how the ground beneath a structure will react.

To conduct research where structures already exist - or to test the soil where future building may be planned - researchers need to conduct experiments outside of the traditional laboratory, or in situ (a Latin term meaning "in the original place"). The NEES program's three field and mobile laboratories make it possible to test on-site and relay the data directly from the field.

Lab vehicles carry equipment that can generate ground vibrations, plus sensors with recording devices to measure the effects. The study of how a structure will react to the ground it stands on during an earthquake-like force is called Soil-Foundation-Structure Interaction, or SFSI.

The University of California at Santa Barbara, in partnership with the University of Southern California and Brigham Young University, has established a permanent field-testing site in the seismically active area of Garner Valley. The mobile lab at the University of California, Los Angeles can conduct testing on full-scale structural and foundation systems. The University of Texas, Austin has three mobile, large-scale shakers that have diverse force and frequency capabilities.