The ability to forecast major volcanic eruptions has huge impact on human life. However, in order to be able to achieve this goal we need a deep knowledge of the active volcanic system and in particular of the dynamics of the eruptions and the timescale on which they occur. The DPhil student will be part of an international, interdisciplinary research group conducting pioneer studies on major active volcanoes located in densely populated areas aiming to understand the shifting from low-active to intense high-explosive major eruptive periods. The student will be generally engaged in field work and state-of-the art micronalytical work. The details of any DPhil project will be defined in discussion with the student, but there are a number of potential avenues of research, including role of degassing processes and use of single crystals to disentangle the volcanic history. Potential field work areas include, but are not limited to Mexico, Caribbean and Italy.