A six-foot-high model levee on peat soil, similar to those in the California Delta, withstood a series of earthquake-simulation tests conducted by researchers from the University of California Los Angeles. More work is needed, however, to study the levees' vulnerability to earthquakes, the experts said. "We were half expecting this thing to settle down noticeably. Our results could very well show that peat is stronger than we thought. The fact that it can move this much and not tear is pretty amazing," said Bob Nigbor of UCLA's Network for Earthquake Engineering Simulation.