Present-day land subsidence risk in the metropolitan cities of Italy

Land subsidence affects many world metropolises, impacting their infrastructure and population. This work showcases an innovative methodology for exposure-vulnerability rating, hazard quantification and risk assessment that integrates remotely sensed information on ground displacement, land cover and settlement characteristics. Land subsidence-induced deformation and structural stress are quantified within the 15 metropolitan cities of Italy, along with the amount of residential/non-residential infrastructure and population exposed. A total of 1.44 out of 2665 km² urbanised land within the 15 cities is at high risk due to significant angular distortions (and, sometimes, additive threat from horizontal strain) affecting very high exposure-vulnerability infrastructure; for more than 2700 buildings there is high likelihood of already occurred/incipient structural damage. This reference knowledge-base on present-day subsidence-induced risk can inform land and risk management at national scale, and provides a baseline for future assessments to build upon with a look to the next decades and sustainable urban development.