A European Space Agency satellite trained on San Francisco has produced conclusive evidence of what the residents of a high-rise condo building have suspected for years: their multi-million dollar residences are slowly sinking into the fault-ridden California dirt.
Engineers previously estimated that the 58-story Millennium Tower, built in 2009, was sinking at a rate of approximately one inch per year, according to the San Francisco Chronicle(Opens in a new window). But new ESA data(Opens in a new window), part of a mission to evaluate building deformities worldwide, show that the tower is sinking at almost double that rate.
The ESA came to that conclusion last month by analyzing more than a year's worth of radar scans from its Copernicus Sentinel satellites. The radar satellites are useful for pinpointing building displacements, the agency says, because their beams cover a wide area and they travel at relatively fast orbital speeds.
In addition to the leaning Millennium Tower, other hotspots have shown up on the Copernicus scans, including many in the San Francisco Bay area. The satellite imagery found that the land of suburban Pleasanton, Calif., has been slowly rising, possibly because of an influx of groundwater after a long drought that ended last year.
In Oslo, Norway, Copernicus found that the city's old train station is slowly sinking into reclaimed land, while the newer buildings next door are safe because they're anchored to bedrock.
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Eventually, the ESA's deformity-seeking satellites could give rise to a new genre of urban planning.
"The Copernicus Sentinel-1 mission is, for the first time, making it possible to launch operational national deformation mapping services," Norwegian Space Center scientist Dag Anders said in a statement(Opens in a new window).
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