Fault Zone (IMAGE) California Institute of Technology Caption This study shows that the plate interface is a patchwork of areas differing in their frictional properties: areas with seismic, or unstable, slip (dark gray patches) and areas with aseismic, or stable, slip (light gray patches). Credit Caltech Tectonics Observatory Usage Restrictions With credit as given above License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.