Unstable sea cave prompts closures

La Jolla streets are shut as repairs begin.

SAN DIEGO — An unstable cave on La Jolla’s coast prompted emergency construction Friday to reinforce the cave and the roadway above it, San Diego officials said.

Geology experts discovered a weakness zone in the sea cave known as Cook’s Crack, which is located underneath Coast Boulevard, and recommended that immediate action be taken, according to a city statement.

James Nagelvoort, director of the San Diego Public Works Department, said the city commissioned a consulting firm to investigate the structure of the cave in preparation for repair work on Coast Boulevard.

The report was finalized and given to the city in June, Nagelvoort said, but officials did not meet with geologists to discuss its findings until Thursday.

The city closed sections of Coast Boulevard Thursday night and initiated an emergency contract to reinforce the cave, according to the statement.

Nagelvoort said the stabilization project has two phases. The first involves injecting a glue-like material into the weaker layer of rock to increase its density and help bind fractures. In the second phase, contractors will reinforce the top of the cave with concrete.

The entire project is expected to close sections of Cave Street and Coast Boulevard to all traffic for about six weeks. The statement said the city will try to accommodate access for nearby residents and businesses.

The construction comes one week after an oceanfront bluff in Encinitas collapsed and killed three women on the beach below.