Interactive: New earthquake fault zones in the San Gabriel Valley

California officials have released the final map of the Sierra Madre fault zone as well as estimated fault lines. Owners of proposed developments in the newly defined zone will generally be required to prove that they are not constructing a building on top of an active fault line. Only further detailed studies can precisely determine if the fault actually crosses any particular property. Local building officials will decide whether a project can be built in the fault zone.

  Fault zone
  Approximately located fault: Geologic evidence strongly suggests this path of the fault.
  Inferred fault traces: Location inferred based on geologic study.
  Concealed fault: Likely buried under many layers of sediment.
Note: Areas where state officials think faulting exists but have no specific evidence for it are shown as gaps in the fault line. A higher level of certainty, "accurately located," is shown as "approximately located" because only small stretches of the map fall within it. Download the official state map here.
Source: California Geological Survey