Seismic risk analysis of buried pipelines: the case of l'Aquila gas network.

The paper analyses the effects of the 6th April 2009 L'Aquila earthquake, in Italy, on the local gas network, by applying a simplified multi hazard loss estimation methodology, following the layout of HAZUS project (FEMA, 2003). Key factors of the methodology are the inventory, the typology and the specific characteristics of the pipelines that help to define the fragility functions for the elements composing the network, as well as the seismic scenarios (seismic hazard) and the geological and the geotechnical characterization that allow to define the susceptibility of the area to landslide and liquefaction that, together with ground shaking, cause major damage on pipelines network. All the available data related to the local gas network and to the geological and geotechnical characterization of the L???Aquila basin have been collected in a GIS environment. Seismic hazard has been evaluated taking into account for both transient ground deformation caused by the seismic waves propagation (ground shaking) and permanent ground deformation (PGD) related to landslides. The loss estimation has been evaluated in terms of repairs per unit length of pipe associated to the seismic demand expressed in terms of peak ground velocity, PGV and permanent ground deformation, PGD, relevant to the 6th April 2009 earthquake event. The produced hazard scenario has been finally used to compare the data of the damage inventory collected in a narrow area by the organization managing the gas distribution network in L???Aquila, with the fragility curves adopted to predict the damage scenario.