The evolution of volcanism following sector collapse

Sector collapses are among the largest volume events to affect volcanic systems, potentially involving the rapid displacement of tens of cubic kilometres of rock. There is growing evidence that such substantial changes in surface loading can have profound effects on the stability of an underlying magma reservoir, potentially manifested through shifts in eruption rate or composition and dominant eruptive behaviour. Nevertheless, a detailed understanding of how and why collapses perturb a magma system is lacking, both because of an absence of historical observations of large sector collapses, and because of the challenges involved in generating high resolution reconstructions of past eruptive activity that span the periods before and after collapse. This project will take advantage of two unusual marine sediment sample sets collected offshore the volcanic islands of Montserrat (Lesser Antilles) and Ritter Island (Papua New Guinea). These samples and cores preserve a record of activity at these volcanoes before and after major collapse events, and can advance our understanding of how volcanism at arc-volcanic systems responds to sudden changes in surface loading.
Ritter Island was the site of the largest historical sector collapse (around twice the size of the Mount St. Helens event in 1980), in 1888, and recent analysis of samples collected in 2016 indicate that unusually evolved magmas were erupted immediately following collapse, and that subsequent rebuilding of the submarine cone has produced rocks that are compositionally distinct from those erupted before collapse. The event provides an ideal opportunity to better understand the nature of post-collapse changes in activity, but inaccessibility means that the volcano has been little studied previously. The 2016 samples were the first collected from the 1888 collapse. More will be collected on a planned research ship expedition in 2020, in which the PhD student would participate.
Montserrat has been subject to multiple large scale sector collapses throughout its history, and provides an opportunity to investigate the impacts of collapse on volcanic behaviour over longer (103-5 year) timescales, thus complementing the higher-resolution, shorter timescale study of Ritter. The student would work with extensive core samples from IODP 340, potentially alongside new samples planned for collection in 2019.
The project student will be based at Birmingham but would work closely with the co-supervisors at Oxford and the Natural History Museum (a CENTA2 Level 1 partner), making use of laboratory facilities at a number of UK institutions. The student will also have the opportunity to build relationships with international collaborators at GEOMAR (Germany) and with international participants in the wider marine research project (including collaborators in Papua New Guinea for the Ritter Island component of the project).
Further details:
Please contact Dr Sebastian Watt - [Email Address Removed]
This project will suit a student with an interest and facility for detailed laboratory work, an enthusiasm for volcanology and an interest in working within a collaborative, interdisciplinary project.