Recent earthquake catastrophes have shown that the same seismic wave that flattens one block can leave the next unscathed. Local variations in factors such as basin shape and soil play a bigger role than previously thought. Through a major collaboration called The Quake Project, a team of engineers and computer scientists at Carnegie Mellon University and the University of California at Berkeley are working with seismologists from San Diego State University to better understand these factors. Led by CMU's Jacobo Bielak, the project aims to develop computational models that can reliably predict ground motion in large basins, information that can help in drafting building codes for safer, economical structures.

As part of this project, several earthquake research groups are working to jointly validate their modeling technologies. These visualizations represent Bielak's recent simulations pursuant to that effort. They model an earthquake in a vertical fault - called a strike-slip fault - typical of the San Andreas and other faults in California. The simulation represents the fault structure as a plane surface embedded within a 3-D volume. A rock layer, one kilometer thick, is supported on a stiffer rock mass. Color (increasing from violet to red) indicates the speed of ground motion in the horizontal direction. Comparing the first image (top) with the second (two seconds later in time) shows how the seismic wave travels rapidly away from the fault.