Multi-risk assessment of a cultural heritage masonry building subjected to both earthquake and volcanic threats

Earthquake protection of cultural heritage buildings is a primary task in Italy. Nevertheless, a large part of the Italian territory is also affected by other kinds of natural hazards which should be considered in risk assessment procedures. The area surrounding Mt. Vesuvius (Southern Italy) is an emblematic case study for the high risk level related to both volcanic and tectonic earthquake hazards. This multi-risk environment makes that area one of the most monitored regions all over the world. In this paper the multi-risk assessment of a 17th Century monumental masonry building subjected to both earthquake and volcanic threats is presented. The building is located in Torre del Greco, a town close to Mt. Vesuvius with the highest exposure level in terms of inhabitants. According to the emergency management plan developed by the Italian Department of Civil Protection, a scenario-based risk assessment was carried out for the cultural heritage building. The following scenarios were considered: (1) a sub-Plinian eruption like that of 1631; and (2) a tectonic earthquake according to the Italian seismic hazard map. In the first scenario, the building structural performance was assessed under: high-intensity vertical roof loads according to an ash fall hazard model; and horizontal pressures and high-temperature material degradation, caused by pyroclastic and lava flows on peripheral masonry walls. In the second scenario, static pushover analysis was performed under code-based gravity loads. Analysis results led to identify hazard sources inducing lack of safety and strengthening methods for multi-risk preservation of the building.