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Though previous studies had found that Venice has stabilised, new measurements indicate that the historic city continues to slowly sink, and even to tilt slightly to the East. "Venice appears to be continuing to subside, at a rate of about 2 mm a year," said Yehuda Bock, a research geodesist with Scripps Institution of Oceanography at the University of California, San Diego, in La Jolla, Calif., and the lead author of the new article on the city’s downward drift. Given that sea level is rising in the Venetian lagoon, also at 2mm per year, the slight subsidence doubles the rate at which the heights of surrounding waters are increasing relative to the elevation of the city, he noted. In the next 20 years, if Venice and its immediate surroundings subsided steadily at the current rate, researchers would expect the land to sink up to 80 mm (3.2 inches) in that period of time, relative to the sea. Bock worked with colleagues from the University of Miami in Florida and Italy’s Tele-Rilevamento Europa, a company that measures ground deformation, to analyse the data collected by GPS and space-borne radar (InSAR) instruments regarding Venice and its lagoon. The GPS measurements provide absolute elevations while the InSAR data are used to calculate elevations relative to other points. Bock combined the two datasets from the decade between 2000 and 2010. In the new study, using the GPS instruments, Bock and his colleagues were able to take absolute readings of the city and its surrounding lagoons. And not only did they find the sinking, but they found that the area was tilting a bit, about a millimeter or two eastward per year. That means the western part — where the city of Venice is — is higher than the eastern sections. — ANI
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