Geologists say that large parts of central Moscow are at risk of collapsing "like a pack of cards" because the ground under some buildings has been weakened by subterranean shopping centres and car parks.
There have been three incidences in the past week when the ground has simply opened up, pulling anything on the surface downwards. An entire section of the busy Leningradsky Prospekt - which is one of the main arteries in and out of Moscow - collapsed overnight, leaving a 32ft crater.
Geologists say that the same could happen to 15 per cent of Moscow "at any moment" and that half of the city's subterranean territory is scarred with "problematic geological nuances". The dramatic road collapse occurred late at night and nobody was hurt; only a parked lorry and construction equipment disappeared into the crater.
But experts warn that it is only a matter of time before people are injured or killed. Moscow's government, a body that has been one of the biggest promoters of underground construction work, is not taking any chances. It has ordered every construction site in the capital to be checked to ensure that building work is not undermining the surface. Under the leadership of Mayor Yuri Luzhkov, Moscow is undergoing its most far-reaching construction boom since Joseph Stalin reshaped much of the city in the 1930s. Riding high on oil profits, the authorities have rushed to approveskyscrapers, underground shopping centres and car parks in order to make the most of every square metre of land.
But now even Mr Luzhkov appears to be nervous. Last week he vetoed the construction of an underground concert hall beneath the celebrated Bolshoi Theatre, arguing that it could cause many of central Moscow's most famous landmarks, including the theatre itself, to collapse.
Mr Luzhkov's critics claim that the construction work he has sanctioned in the past decade has been carried out too quickly without bothering with geological or architectural surveys.
They charge that the ground beneath Moscow has been gouged out in too many places in areas criss-crossed with underground rivers, shifting ground waters and unstable subsoil. They also argue that the skyscrapers so beloved of Mr Luzhkov are, by their very nature unsuitable for Moscow's unpredictable foundations as they put greater pressure on the ground below than more traditional structures.
Marina Khrustaleva, of the Moscow Architecture Preservation Society, warned that the fashion for underground construction was growing despite the obvious risks. "It seems to be an unwritten rule that any new building has to have at least a one-level underground car park," she said. "If I had my way I would ban any underground building in the historic centre."
Though the authorities have begun to pay lip service to the problem, their enthusiasm for such projects seems undimmed; a huge underground car park is to be slotted in less than 200 feet from Red Square before 2008.
Vadim Mikhailov, the head of an organisation called "Digger-Spas" which helps the emergency services rescue people stuck beneath Moscow, believes that the authorities are sleep-walking into a crisis. "It seems that the building boom and money is everything while human lives come last," he said. "Moscow is not a simple city. There are many hollow cavities, shafts, and shifting sands beneath its surface. We are afraid that we are heading for some kind of huge catastrophe unless something is done." Mr Mikhailov argued that the entire area beneath the city needed to be properly surveyed and a new geological map of subterranean Moscow drawn.