标题：Brief communication: Remotely piloted aircraft systems for rapid emergency response: road exposure to rockfall in Villanova di Accumoli (central Italy)
摘要：The use of remotely piloted aircraft systems (RPASs) in geosciences is oftenaimed at the acquisition of an image sequence to produce digital models andorthophotographs of the topographic surface. The technology can be appliedfor rockfall hazard and risk assessment. To study rockfalls, an approachconsists in the application of numerical models for the computation ofrockfall trajectories. Data required for such simulations include digitalterrain models, location of the instability source areas, and the mechanicalproperties of the terrain. In this article, we present an analysis of theearthquake-triggered rockfall that occurred along the SP18 in Villanova diAccumoli (Lazio, central Italy) during the seismic sequence that started on24 August 2016. A survey with a multicopter was carried out to obtain asurface model of the terrain and identify and characterize thesource areas and other instable blocks in areas not accessible in thefield. The investigated area extends for 6500 m2 and was covered by161 photographs that were used to obtain an orthophoto with a groundresolution of 2.5 cm and a digital surface model with a ground resolutionof 20 cm × 20 cm, which was processed and fused with GNSSreal-time kinematicdata. To obtain a map of potential rockfall trajectories, we run thenumerical model STONE, using as origin of the boulders both source areasmapped in the field and pixels with a slope angle above a selected threshold.Results showed that only the part of the road SP18 already affected by therockfall was exposed to further rockfall impacts. In particular, it wasobserved that 29.2 % (i.e. 12 123) of the 41 500 simulated trajectoriesmay potentially reach or cross this tract of the road. Based on these data,limited protection measures were suggested. The combined use of RPAS data,fused with ground GPS points, an accurate geomorphological survey, andterrain static and dynamic parameters from the literature allows fast,low-cost, and replicable rockfall numerical modelling useful for emergencyresponse and adoption of proper protection measures.
