The 50th anniversary of one of California’s deadliest earthquakes has spurred calls for action to reduce risks in the seismically active state.

The Sylmar quake hit just after 6 am on February 9, 1971, causing the deaths of more than 60 people and leading to hundreds of millions of dollars in property damage. The epicentre was about 14 kilometres north of San Fernando in Los Angeles County.

The Insurance Information Institute says the anniversary highlights the importance of retrofitting homes to withstand severe shaking, with many pre-1980 buildings vulnerable due to raised foundations.

“The potential cost of US earthquakes has been growing because of increasing urban development in seismically active areas and the vulnerability of older buildings, which may or may not have been built or upgraded to current building codes,” California-based Director, Strategic Communications Janet Ruiz says.

Most of the deaths from the 6.5 magnitude quake 50 years ago occurred when a hospital collapsed.

The publicly managed, privately financed California Earthquake Authority (CEA), formed after the 1994 Northridge earthquake, provides two-thirds of residential earthquake cover in the state, with policies sold through participating insurers.

The CEA says California experiences more than 100 quakes a day, although most cause little or no damage. The most severe by intensity include the 7.9 magnitude San Francisco earthquake of 1906.

“On the 50th anniversary of the Sylmar quake, California’s homeowners, renters and businesses should financially prepare for the possibility of an earthquake,” Ms Ruiz said.