Calcite Veins (IMAGE) University of Wisconsin-Madison Caption The white calcite 'veins' of the Loma Blanca fault are evident in this slab of rock on the fault. These veins of calcite reveal a record of fluid-driven earthquakes clustered together on a fault typically characterized by less frequent, periodic earthquakes caused by mechanical stress. They helped UW-Madison researchers trace the oldest and longest earthquake record ever documented. Credit Courtesy of Laurel Goodwin and Randy Williams, UW-Madison Usage Restrictions None 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.