New earthquake faults discovered in Napa

Previously unmapped earthquake faults ruptured during the Aug. 24 magnitude-6.0 South Napa earthquake, surprising both scientists and homeowners. In the Browns Valley neighborhood, one section of the fault cracked through homes, splitting foundations and damaging some houses so severely that they were evacuated. The California Geological Survey is studying the possible fault strands and is working on a regulatory map.

  Moderate building damage

  Severe damage

  Newly discovered faults

  Previously mapped faults

  Possible fault strands under study

Graphics reporting by Rosanna Xia and Rong-Gong Lin II

Sources: U.S. Geological Survey, California Geological Survey, city of Napa