The 22 August, 2006, anomalous rock fall along the Gran Sasso NE wall (Central Apennines, Italy)

It is described the rock fall event occurred along the Gran Sasso massif (Central Apennines, Italy) on 22 August, 2006, when a limestone block, with an estimated volume of about 30,000 m(3), fell from the sub-vertical NE wall nearby the Como Grande peak, the highest peak of the Italian Apennines. Despite the small rock volume involved in the landslide, the rock fall deposits covered an area of about 35,000 m(2), a giant and abrasive dust cloud was generated by the atmospheric pressure waves (air blasts) induced by the rockfall impact and determined destructive effects over an area of about 110,000 m(2) at the base of the slope. Moreover the dust cloud covered a distance of about 3 km, thus reaching the village of Casale San Nicola and the A24 motorway that was temporarily closed for security reasons. The seismic noise generated by the rock fall was recorded by the National Institute of Nuclear Physics seismometric devices located in the Gran Sasso underground laboratories (LNGS).