The natural and man-induced subsidence of the Ravenna Area.

The town of Ravenna, on the south-eastern edge of the Po River Plain, 10 km from the present shoreline, is subject to a high regional natural subsidence, near to the maximum values of all the Po plain, active from at least the Pliocene and during all the Quaternary. In the last decades Ravenna and its surroundings have been affected by a man-induced subsidence of up to fifty times the natural rate, mainly due to water pumping for civic usage and then to the extraction of methane. The subsidence reached peaks of high risk and the related effects of these became critical. The progressive reduction in the last two decades of underground water use brought the subsidence close to natural rates, but the negative consequences of elevation loss in the near future due to coastal erosion, higher storm surges and the risk of river floods, still remain.