Real cause of Malibu sinkhole: As Nicolas Cage's $10.5m mansion is SWALLOWED... A-list stars next at risk are revealed and expert admits fears it's spreading

It's one of the most expensive pieces of real estate on the planet where the average home goes for between $3.5 and $5.5 million. 

But as veteran actor Nicolas Cage discovered this week, the spectacular sea views and celebrity neighbors come at a steep price that isn't just counted in dollars.

Celebrity enclave Malibu is back in the headlines this week after Cage's stunning $10.5 million beachfront pad was left languishing in a large sinkhole following severe storm surges caused by Tropical Storm Marie out in the Pacific.

According to Kyle Tourjé, Vice President at leading Los Angeles structural repair firm Alpha Structural, there are several possible culprits for the calamity – all exacerbated by the high waves that pounded the California coastline over the weekend.

'We get a lot of these calls,' he told the Daily Mail in an exclusive interview. 'A lot of these houses are built on sea wall that's very old.

'The house above might be newer but what's below could be 70 years old. When you get these surges, they can pull the dirt out from underneath the sea wall which causes sinkholes.

'Sometimes the sea wall isn't high enough which has the same effect. These are very common sea wall problems.

'Then, in Malibu, most sewage goes into seepage pits, and they can also damage soil and cause subsistence if the seawater gets in.'

Exclusive aerial photos taken by the Daily Mail show the massive damage done to Cage's property, which is boarded up at the front while the hole can clearly be seen at the back.

Part of the road leading to the property is also in the hole – something that will cause extra complications for 62-year-old Cage, according to Tourjé – while a porta-potty can also be seen trapped inside.

Tourjé says Cage could simply have got unlucky, with his property bearing the brunt of the surges while his neighbors' properties were spared.

But he says most prime seafront properties in Malibu are vulnerable to storm surges – and that means Cage isn't the only big name who could find himself in trouble.

Further down the coast from Cage's mansion is Carbon Beach – also known as Billionaire's Beach – whose past and present big-name owners read like a veritable who's who of leading lights in tech and film.

Topping the list is Oracle co-founder Larry Ellison who owns multiple homes on the tony stretch of sand, where neighbors include record executive Lou Adler and Friends star Courteney Cox, and up until March, rapper Dr Dre, who sold his beach house for $16.5 million. 

Former residents include Wonder Woman star Gal Gadot, former CBS chief executive Les Moonves and entertainment mogul David Geffen.

Another prominent celebrity enclave is Malibu Colony – again directly on the beach – where residents include Tom Hanks, Bill Murray, Miley Cyrus, and Jonah Hill - who listed his property for $13.3 million earlier this year. 

Previous owners include Halle Berry as well as Golden Age stars such as Frank Sinatra, Judy Garland and Bing Crosby.

'There are lots of reasons why you'd want to live in Malibu,' Tourjé said. 'You have world class properties, world class views, world class privacy.

'But you do need, when purchasing a property there, to get it evaluated and make sure you know the age of the sea wall.

'If you already live there, you need to regularly get the foundations inspected, the sea wall inspected and the plumbing checked – you have to be proactive about maintaining it to make sure your property isn't at risk of subsidence.'

Malibu is also vulnerable to wildfire damage, with large stretches of the California town – particularly on the Pacific Palisades end – still pockmarked with burned out gaps and empty foundations nearly two years after the devastating Palisades Fire ripped through the area.

Along with Spencer Pratt, who famously lost his Pacific Palisades home in the blaze, Paris Hilton, Milo Ventimiglia and Mel Gibson all lost beachfront properties in Malibu – with the sea wall in the areas hit by the blaze also left badly damaged.

Although damage from the blaze is still being repaired, Tourjé said homes – such as Caitlyn Jenner's – on the rocky hillsides on the other side of the Pacific Coast Highway are also put at heightened risk by storm surges, especially in the burn areas.

'Malibu has a challenging history of landslides,' he noted. 

'If you're on a hillside, the risk is still there so managing the foundations and things like drainage is critical.'