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posted by martyb on Monday November 28 2016, @03:58PM   Printer-friendly
from the what-goes-up-must-come-down dept.

The ESA's web report discusses subsidence and (more rarely?) elevation of the earth's surface. It works especially well in cities, “down to millimetres. The technique works well with buildings because they better reflect the radar beam” They're studying the phenomenon worldwide.

The Sentinel-1 satellites have shown that the Millennium Tower skyscraper in the centre of San Francisco is sinking by a few centimetres a year. [...] Completed in 2009, the 58-storey Millennium Tower has recently been showing signs of sinking and tilting. Although the cause has not been pinpointed, it is believed that the movements are connected to the supporting piles not firmly resting on bedrock.

The Register succinctly summarizes the whole situation in this report:

It was expected to sink less than 10 inches during its lifetime. It's already slumped 16 inches, is listing a few inches to the northwest, and it could sink a further 31 inches. The European Space Agency today said its Sentinel-1 satellites, having scanned the city's surface, have found that the building is disappearing into the ground at a rate of a few centimetres a year.

The problem appears to be that it was not built all the way down to the bedrock, and instead is sitting on a concrete slab with piles that go down just 60 to 80-feet into an underlying layer of landfill. Lawsuits against the developers are, as expected, in flight.

It's alleged that the city's building inspectors knew back in 2009 that the tower was sinking but did nothing about it – not even alerting the public nor the apartments' owners. San Francisco magazine's Lauren Smiley and Joe Eskenazi have detailed this ongoing clusterfsck at length here; it's worth the read.

The Register article also provides a copy of the ESA's displacement map for San Francisco with the tower's location marked and provides a link to a higher-res map.


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  • (Score: 2, Informative) by Anonymous Coward on Monday November 28 2016, @10:02PM

    by Anonymous Coward on Monday November 28 2016, @10:02PM (#434251)

    there's the infamous 1928 St. Francis Dam disaster in California, in which the dam had developed new cracks and leaks over a 2 year period, and each time was inspected and declared safe, with the final inspection done by the top official the day before the catastrophic failure.

    A little context [smithsonianmag.com] would have been nice:

    Early in the morning on March 12, the day of the disaster, dam keeper Tony Harnischfeger was doing his normal daily inspection when he found something distressing; a rather significant leak on the west abutment was pouring out muddy water - a potential sign that foundation material was being washed away. Harnischfeger called Mulholland, who rushed to the site accompanied by his deputy, Harvey Van Norman. Arriving around 10:30 a.m., they inspected further, but discovered, much to their relief, that the water was not muddy at the point of origin of the leak. This left them convinced that construction nearby had made the water muddy and the dam itself was not in immediate danger of collapse. They returned to Los Angeles and ate “a late lunch,” apparently unconcerned. Around 11 p.m., Harnischfeger completed his usual nightly inspection. Less than an hour later, the dam broke.

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