Landslides, volcanism and volcano-tectonics: the fragility of the Neapolitan territory. Cities on Volcanoes 10 Meeting – Napoli 2018

Abstract

Small landslides to large debris flows and debris avalanches affected the Neapolitan territory surrounding the active volcanoes of the area: Vesuvius, Campi Flegrei and Ischia. Their variable intensity explosive eruptions produced significant quantities of loose pyroclastic material on the slopes of the volcanoes and of the surrounding reliefs. Remobilization processes of this material occurred during and soon after large explosive eruptions, although their intensity and frequency decreased during inter-eruptive periods. The intensity of these processes varies with the different eruptions and is strongly dependent on availability of fine ash in proximal and distal areas. The areas involved varies from hundreds to millions square meters. The syn-eruptive debris flows of the Vesuvius 472 AD eruption are described in detail. Huge ground uplift of the central part of the Ischia resurgent caldera generated debris/rock avalanches, which likely caused tsunamis. Archaeological sites affected by syn-eruptive debris flows have been selected to show the effects of their deposition. Hydraulic risk and risk mitigation actions, emergency management and preparedness measures will be discussed in one of the areas mostly affected by recent debris flows. At Ischia the characteristics of debris/rock avalanches and lahars related to the resurgence and to the reactivation of volcanism will be discussed.