LOOK: Sentinel 1 Satellite Proves Millennium Tower in San Francisco is Sinking
Detailed images from Sentinel-1 satellites reveal that one of San Francisco's prominent skyscrapers, Millennium Tower, sinking little by little every year.
A statement by the European Space Agency, or ESA, on its website, said that the 58-storey building has shown notable signs of sinking and tilting. As a matter of fact, locals have now dubbed Millennium Tower as "the leaning tower of San Francisco."
"To probe these subtle shifts, scientists combined multiple radar scans from the Copernicus Sentinel-1 twin satellites of the same area to detect subtle surface changes - down to millimetres. The technique works well with buildings because they better reflect the radar beam. It is also useful for pinpointing displacement hotspots over large areas, thanks to Sentinel-1's broad coverage and frequent visits," ESA said.
— ESA (@esa) November 25, 2016
Based on Sentinel-1 satellite latest data between February 22, 2015 and September 20, 2016, the Millennium Tower is sinking at least 40 millimeters a year in its line of sight (the direction that the satellite is looking at the building), the Daily Mail reports. The $350 million dollar luxury building has, however, already sunk 16 inches in total since it first opened its doors to the public in 2009.
The exact cause has not yet been determined. City agency, the Transbay Joint Powers Authority, faults the The Millenium's "inadequate foundation," which is not anchored to bedrock, supported only by piles driven 18 to 27 meters into landfill, according to an article by ABC.
The same phenomena is seen in a number of European cities, such as Norway, where experts find the the data from the San Francisco study useful. "Experience and knowledge gained within the ESA's Scientific Exploitation of Operational Missions programme give us strong confidence that Sentinel-1 will be a highly versatile and reliable platform for operational deformation monitoring in Norway, and worldwide," said John Dehls from the Geological Survey of Norway.
"The Sentinel-1 twins provide 'radar vision' for Europe's Copernicus environment monitoring programme. In addition to watching land movements, they feed numerous other services for monitoring Arctic sea ice, routine sea-ice mapping, surveillance of the marine environment, mapping for forest, water and soil management, and mapping to support humanitarian aid and crisis situations," ESA explained.