Suchergebnisse

Abstract. This study presents an historical database of flash flood events in the Campania region of southern Italy. The study focuses on small catchments characterized by intermittent flow, generally occurring during and after heavy rainstorms, which can be hydrologically defined as small Mediterranean catchments. As the outlet zones of these catchments (consisting mainly of alluvial fans or fan deltas) are highly urbanized in Campania, the population living in the delivery areas is exposed to high risk. Detailed scrutiny and critical analysis of the existing literature, and of the data inventory available, allowed us to build a robust database consisting of about 500 events from 1540 to 2015, which is continuously updated. Since this study is the first step of a longer project to perform a hazard analysis, information about time and site of occurrence is known for all events. As for the hazard analysis envisaged, collecting information about past events could provide information on future events, in terms of damage and also spatial and temporal occurrence. After introducing the issue of flash floods in Italy we then describe the geological and geomorphological settings of the study area. The database is then presented, illustrating the methodology used in collecting information and its general structure. The collected data are then discussed and the statistical data analysis presented.

Abstract. Among the almost 1400 landslides triggered by the shocks
of the 2016–2017 central Italy seismic sequence, only a limited number, all
classifiable as rockslides, involved volumes larger than 1000 m3. Four
of these failures, including the three largest among the documented
landslides, were described in terms of structural and geomechanical
investigations in a previous paper. In this study, the estimated
acceleration time histories at the rockslide sites were evaluated through a
2D simplified numerical model accounting for the attenuation phenomena and
for the topographic effect of the rock cliffs from which the slide detached.
Instantaneous stability analyses were carried out to obtain insights into
the variability of the instantaneous margin of safety along the motion, over
the entire spectrum of mechanisms that could be activated. Finally, some
general suggestions on the pseudo-static verification method for
3D cases are proposed, which represent useful indications to
hazard evaluation at local and regional scales.

According to the usual definition, risk is a combination of Hazard, Exposure and Vulnerability, representing the global damage amount connected to a particular event that may occur in a given area in a prefixed return time. According to the previous definition, a "multihazard risk analysis" needs a methodological approach able to combine in terms of effects several different natural events that may occur in an area. This analysis has the purpose of defining political and technical programs for risk mitigation, so to address public resources where priorities are high. Bridges play a primary role in the development and application of such analysis, showing high vulnerability towards great natural hazards such as floods and seismic actions. In this paper the results of a multi hazard analysis carried out taking into account seismic and hydraulic hazards on bridges in Capitanata region (FG - Puglia Region, South Italy) are presented. This work has been developed in a research project, named "Studio di Fat- tibilità per il Monitoraggio e la Messa in Sicurezza delle Aree Urbane a Rischio di Stabilità Statica e Vulnerabilità Strutturale nella Città e Provincia di Foggia" managed by the Autorità di Bacino della Puglia together with the Technical University of Bari. The proposed approach is based on the definition of a synthetic Index, named Priority Index, that simply defines the global risk level associated. It summarizes several information connected to the main structure properties, related to seismic and hydraulic local effects, to the exposition and to the functionality. The Seismic Damage Index is strictly connected to the structural behavior and its response to seismic actions expected in the well defined area. It compares the spectral acceleration representing the site design spectrum with two other spectral acceleration values considered equivalent to Hazus median damage function accelerations, corresponding to slight damage and complete damage for the structure. The Hydraulic Damage Index furnishes a ...