City of San Diego officials say the instability of a section of cliff along the shore of La Jolla has them “very, very concerned” as they launch a six-week plan to prevent a collapse.

A sea cave called Cook’s Crack, located underneath Coast Boulevard north of downtown San Diego, will be filled to help protect the road above along with a water main, a sewer main and a storm drain main.

“When we went in there and observed the cave what we’ve noticed is the strong rock material from above… is actually started to break away and we’re starting to see the weaker material and that’s what’s getting our attention,” said Director of Public Works James Nagelvoort.

“The type of failure of this type of situation is not a slow settlement,” said Nagelvoort. “You start to get erosion underneath, and from above and the street, the type of failure is a collapse. That’s why we have to take immediate action.”

The road was closed Thursday evening and will remain closed for approximately six weeks, city officials said.

Traffic along Coast Boulevard at Cave Street will be diverted.

The plan is to plug the sea cave to remove the water and then from above fill the void with a sand/slurry concrete mix.

They will need 2,500 cubic yards or 300 concrete trucks full of mix to fill the void, the city's engineer said.

The owner of the nearby Brockton Villa Restaurant said the closure will directly impact his business in the normally busy summer season.

“Having no notification of the situation is really alarming,” Heine said. “They’re allowing the public to walk on the sidewalk.

He was told the interruption may last up to two weeks.

“Six weeks? I might as well close my business,” he said. “This is the busiest time of year.”

He said his staff was on the phone trying to get a hold of customers who have booked reservations to let them know about the road closure.

He said he can expect the sidewalk to be open to pedestrians but customers will need to park farther away and walk to his restaurant.

The sea cave has been in existence for many years but has been slowly eroding over the years.

Studies in the early 2000s did not alert city officials to any issues with the sea cave but suggested that city engineers keep an eye on the location.

When city of San Diego engineers began looking into fixing Coast Boulevard as part of an initiative to repair issues with local roads, inspectors noticed a change in the cave's stability.

Please be advised: The City today will begin an emergency construction project to stabilize a zone of weakness in a local sea cave located underneath Coast Blvd. Sections of Cave St. and Coast Blvd. will be closed temporarily to all traffic for about 6 weeks. pic.twitter.com/moEspdvsmO — City of San Diego (@CityofSanDiego) August 9, 2019

The announcement Friday marks one week since a bluff collapsed in Leucadia, killing three women who were sitting on the beach below the cliff.

Nagelvoort said as tragic as the bluff collapse was, it is part of the ongoing erosion of our coastline.

"The coast of California is losing land about a foot a year forever," he said.

Coast Boulevard – near Cave Street and La Jolla Cove – remained closed Saturday morning as crews continued to work on the sea cave project.

The scenic zone is a popular attraction among both locals and tourists, but navigating the area due to the road closure may be more challenging than usual as work continues on the sea cave project.

We visit “Sunny Jim’s Cave” in La Jolla, to see Sunny himself.