Il sistema di monitoraggio della Grotta del Farneto (Bo).

Farneto is the most famous cave of the Regional Natural Park of “Gessi Bolognesi e Calanchi dell’Abbadessa”. The cave, discovered in 1871 and explored in the early years of the XXth century, after decennia of abandonment, was closed to the public in the early 90s because of mass movements that had obstructed the entrance. After important stabilisation works the cave was reopened to the public in October 2008. In order to evaluate the stability conditions of the areas open to visitors, the Department of Earth and Environmental Sciences of Bologna University is managing data (on an hourly basis) measured by a monitoring system composed of six extension meters and two clinometers placed in those areas having the most critical situations. Together with these instruments (that measure opening and closure of rock discontinuities or rotation of potentially unstable blocks) also three monitoring devices for temperature and relative humidity have been put in place. From the data analysis of three years of monitoring it is clear that the small movements are independent from rainfall and relative air humidity, while some of the changes are inversely correlated to temperature variations, with cycles of thermal contraction and dilatation. However, despite this cyclic behavior, the recorded deformations appear to be progressively increasing over the three years.