Precariously Balanced Rocks Suggest San Jacinto, San Andreas May Have Ruptured Together

Stacked in gravity-defying arrangements in the western San Bernardino Mountains, granite boulders that should have been toppled long ago by earthquakes are maintaining a stubborn if precarious balance. In puzzling out why these rocks still stand, researchers have uncovered connections between Southern California’s San Jacinto and San Andreas faults that could change how the region plans for future earthquakes. (Read the full story)