Comparison of event landslide inventories: the Pogliaschina catchment test case, Italy
Abstract. Event landslide inventory maps document the extent of populations of landslides caused by a single natural trigger, such as an earthquake, an intense rainfall event, or a rapid snowmelt event. Event inventory maps are important for landslide susceptibility and hazard modelling, and prove useful to manage residual risk after a landslide-triggering event. Standards for the preparation of event landslide inventory maps are lacking. Traditional methods are based on the visual interpretation of stereoscopic aerial photography, aided by field surveys. New and emerging techniques exploit remotely sensing data and semi-automatic algorithms. We describe the production of two event inventories prepared for the Pogliaschina catchment, Liguria, NW Italy. The two inventories show landslides triggered by an intense rainfall event on 25 October 2011, and were prepared through the visual interpretation of digital aerial photographs taken three days and thirty-three days after the event, and processing a very high resolution image taken by the WorldView II satellite four days after the event. We compare the two inventories qualitatively and quantitatively, using established and new metrics, and we discuss reasons for the differences and the similarities between the landslide maps. We expect that the results of our work can help deciding on the most appropriate method to prepare reliable event inventory maps, and to outline advantages and the limitations of the different methods.