Volcanic hazards and risk have not been considered in previous global assessments by UNISDR as part of the biennial reports on disaster risk reduction. This book developed as a consequence of Global Volcano Model (GVM) being invited to make such an assessment by UNISDR for its 2015 report. GVM worked in close collaboration with the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) to contribute four background papers for the 2015 Global Assessment Report (GAR15) of UNISDR. These background papers contain a lot more information than could be included in GAR15 and can be construed as the evidence on which UN ISDR have been able to include volcanic risk into their report. Although the background papers were placed on the UNISDR website they would have become part of the ephemeral grey literature that increasingly pervades scientific publication. Thus the decision was made to publish the reports together as an open access e-book with the support of UNISDR.

The book represents the efforts of the global volcanological community to provide a synthesis of what we understand about volcanoes, volcanic hazards and the attendant risks. The book owes its existence to the efforts of many scientists from many countries. There are over 130 authors from 47 countries. Members of the World Organisation of Volcano Observatories (WOVO) have been immensely helpful and collaborative in providing information for the country profiles and making sure that the facts are correct. Outside of those who have directly contributed are many thousands of scientists throughout the world who have provided the data and scientific analysis within the peer-reviewed literature to contribute to the collective knowledge, which we have tried to synthesise. There will be shortcomings and omissions in any endeavour of this kind. GVM and IAVCEI have the ambition to carry out future global analyses to reflect advances in knowledge and to address shortcomings and omissions in this inaugural attempt at a globalsynthesis.