Very few earthquake faults in California have been mapped over the past two decades despite an ambitious campaign launched in the early 1970s to help scientists learn more about the state's seismic activity.
The Los Angeles Times reports only 23 maps have been drawn since 1991 and there haven't been any between 2004 and 2011 because of budget cuts.
State officials estimate there are roughly 300 maps to draw and even more to revise, which accounts for about 2,000 miles of faults statewide.
Public safety may be affected because a ban on new construction atop faults is enforced only for those formally mapped by the state.
The issue has arisen lately because of several new developments planned along the Hollywood fault, which has not been officially mapped.