During the 1989 Loma Prieta earthquake in California, a bridge on Highway 101 near Watsonville supported by piles in soft soil collapsed, and sand boils erupted through the Oakland Airport runways and Bay Bridge approach. UC Davis researchers are employing a powerful technique to test the earthquake safety of such structural foundations: the use of a centrifuge to simulate gravity forces that shakes to simulate earthquake acceleration forces. Bruce L. Kutter, an associate professor of civil engineering, will discuss how centrifuge tests can help people understand how structures behave when the ground shakes, as well as how designs can be improved to withstand those forces. In the Loma Prieta examples, the centrifuge revealed some heretofore unreported phenomenon in the earthquake damage process. In another study, motivated by the new Harbor Freeway in Los Angeles, researchers using the centrifuge found that sound walls supported by a new, more economical retaining wall known as "mechanically stabilized earth" is potentially a safe alternative for the concrete retaining walls currently favored. Kutter and former UC Davis graduate student John A. Casey, now a bridge engineer, will present the papers in session No. 241 at 8:30 a.m., Thursday, Jan. 16, at the Sheraton Washington Hotel. For general information about centrifuge testing, media should contact Kutter at (916) 752-8099; for information about the retaining wall test, media should contact civil engineering professor Karl Romstad at (916) 752-1755.