Planning in advance to prepare for and respond to a natural hazard-induced disaster-related emergency is a key action that allows decision makers to mitigate unexpected impacts and potential damage.To further this aim,a collaborative,modular,and information and communications technology-based Spatial Data Infrastructure (SDI) called SIRENE—Sistema Informativo per la Preparazione e la Risposta alle Emergenze (Information System for Emergency Preparedness and Response) is designed and implemented to access and share,over the Intet,relevant multisource and distributed geospatial data to support decision makers in reducing disaster risks.SIRENE flexibly searches and retrieves strategic information from local and/or remote repositories to cope with different emergency phases.The system collects,queries,and analyzes geographic information provided voluntarily by observers directly in the field (volunteered geographic information (VGI) reports) to identify potentially critical environmental conditions.SIRENE can visualize and cross-validate institutional and research-based data against VGI reports,as well as provide disaster managers with a decision support system able to suggest the mode and timing of intervention,before and in the aftermath of different types of emergencies,on the basis of the available information and in agreement with the laws in force at the national and regional levels.Testing installations of SIRENE have been deployed in 18 hilly or mountain municipalities (12 located in the Italian Central Alps of north Italy,and six in the Umbria region of central Italy),which have been affected by natural hazard-induced disasters over the past years (landslides,debris flows,floods,and wildfire) and experienced significant social and economic losses.