La sequenza sismica dell'Italia centrale del 24 agosto e successive: contributi alla conoscenza e la banca dati degli effetti di superficie

The effect of earthquakes on structures and landscape can basically be divided into two types: direct and secondary effects. The direct effects are related to the deformation of the ground at the fault whose breakage has generated the seismic event and the effects are limited to an area that is short and close to breakage. The secondary effects resulting from the temporary passage of seismic waves may, however, also affect very large areas, causing a widespread presence of permanent effects on the Earth's surface which may affect very large areas, which, in relation to the length of the fault and the magnitude released by the event can be in the order of thousands of km2. Following the seismic events commenced on 24 August 2016 (M6.0) and continued with the shocks of October 26 (M5.4 and M5.9) until October 30 (M6.5), the Unicam GeomorphoLAB Group has mapped and computerized about 4000 permanent deformations on the Earth's surface recognized in an area of over 6000 km2: fractures to the ground, activation and reactivation of large landslides and DGPV, dolines, mud volcanoes and liquefaction phenomena, landslides and small dams, changes in the water regime of the springs and the flow of rivers, cracks and /or fractures and / or deformations on network infrastructures, etc. The present work, therefore, based on the database and the GIS on surface effects, aims at representing a cognitive and interpretative contribution to the surface evidence produced during the seismic crisis of central Italy, looking, based on correlations with the seismic events that affected Umbria-Marche in 1997 and L'Aquila in 2009, to verify and implement, if necessary, the ESI scale which, in the specific case, seems to underestimate its effects. The analysis allowed to verify a high number of surface effects related to fracturing and seismic cracking and deformations on road and network infrastructures and, instead, a low number of activations and / or reactivations of landslides or subsidence. Although small, very significant is the number of variations of the water regime of the springs