Only 23 maps have been drawn since 1991 and there haven't been any between 2004 and 2011 because of budget cuts, the Los Angeles Times reported Sunday. More than 500 maps were published over a 20-year period beginning in 1971.
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. New buildings located near faults that have been mapped are required by law to perform extensive testing to ensure the structures aren't on top of the fissures.
The issue has arisen lately because of several new developments planned along the Hollywood fault, which has not been officially mapped, even though the state has known about its existence for decades.
State officials hope to complete mapping the Hollywood fault by 2014.
The state geologist's budget has dropped from $9.1 million in 2001 to $2.9 million for the current fiscal year. State geologist John Parrish said enough funding has been found to restart the mapping program last year.
"We try to perform as best we can do," Parrish said.
While many faults have already been extensively researched by scientists, experts say it's crucial to complete the mapping to keep new structures away from dangerous areas straddling faults.
"Then there's no mistake (about) the red line," said retired state geologist Robert Sydnor. "It helps at the political level: the city council and the mayor cannot somehow override" it.