Guidelines and metadata model for a repository of volcanic samples

The volcanological community manages heterogeneous types of data acquired during research projects and monitoring activities of volcanoes. These data consist of both continuous and discrete measurements and observations, which are carried out by ground-based networks and remote sensing instruments, or during field surveys and laboratory analyses. Many types of volcanological research are largely based on the accurate sampling of rocks erupted during past and ongoing volcanic activity. Each sample represents a "physical object" which should be identified and archived before part of it is removed for analytical purposes. In this context, we recommend assigning the collected samples unique and persistent identifiers, such as the International Generic Sample Number (IGSN). However, although the IGSN allows recording the most essential information of the collected samples (e.g. geographic location, sampling method, and collector), the predefined metadata fields are not exhaustive for volcanic samples, which require additional information such as type and timing of the eruptive event, sample temperature, and texture. Here we design the guidelines necessary to facilitate communication between and search of multiple sample repositories and databases run by disparate institutions. To this aim, we build a metadata model, which integrate the IGSN metadata with supplementary information necessary for the monitoring and research activities carried out by the volcanological community. The long-term curation of collected materials is an important investment for the future. Indeed, these collections are a resource for the production of volcanological data, they reduce the need for repeated sampling, they preserve samples that can no longer be collected, and they allow repeat analyses to be made. The primary aim of this work, based on discussion within the EUROVOLC project, is to provide the basic information for populating a relational database structure in the future for the description of different volcanic samples, physically located in different physical repositories and institutions, in order to facilitate future sharing between different groups of scientists and more complete volcanological studies, by means of the proposed metadata structure.