Investigating the volatile evolution and decompression rate of high-intensity basaltic eruptions

Knowledge of the driving factors in generating highly explosive volcanic eruptions has been mostly focused on felsic (evolved melts high in silica) eruptions. Nevertheless, mafic (less evolved melts high in magnesium) eruptions of similar explosivity intensity have yet to be studied, even though mafic volcanism is the most common type of volcanic activity on Earth, and they could also trigger devastating societal and environmental impacts.

This project aims to improve understanding of mafic volcanism by reconstructing the chemical evolution and volatile budgets from melt inclusions, small droplets of melt trapped during crystal growth that preserved the history of the most explosive mafic eruptions in the geologic record. This study will provide insights on the timescales over which mafic magmas ascend to erupt explosively, which can be used to inform eruption response efforts and forecasts.

The research team will collaborate with the U.S. Geological Survey’s Hawaiian Volcanic Observatory (HVO-USGS) to disseminate knowledge among global volcanic monitoring and risk assessment agencies. The work will also broaden the global use of geochemical techniques in volcano monitoring and response by supporting a module in the Center for the Study of Active Volcanoes (CSAV) summer course.

This project will support graduate and undergraduate students through training in different micro-analytical techniques at Cornell and HVO, and their applications to understand eruptions. Results from this project will be incorporated into Earth Materials and Volcanology courses at Cornell. Finally, this project will enhance the infrastructure for research and education by establishing collaborations between Cornell University, HVO-USGS, the University of Manchester, LDEO-Columbia University, the University of Auckland, Caltech, and Syracuse University.

High-intensity explosive eruptions (sub-Plinian, Plinian, and ultra-Plinian, with a volcanic explosivity index of 6+) result in global environmental effects and have great potential for devastating societal impacts. Among these eruptions, mafic eruptions are the least studied and represent a critical end-member urgently needing further investigation.

Of particular interest is the determination of their magma decompression rates (dP/dt), as this parameter plays a crucial role in setting the style of volcanism in the eruption dynamics for basaltic magmas. This project will study the volatile evolution and decompression of basaltic Plinian to sub-Plinian eruptions. These eruptions represent some of basaltic volcanism's most catastrophic and least understood end-members.

Reconstructing their eruption histories will address the following questions: 1) What is the record of pre-eruptive conditions and degassing that characterizes basaltic Plinian eruptions? To accurately constrain magmatic conditions, the evolution of volatile saturation and degassing before and during the eruption, and decompression pathways, the team will use olivine-hosted MIs. 2) What are the decompression rates of basaltic Plinian eruptions?

Estimates of magma decompression rates for the proposed eruption case studies need to be improved or constrained indirectly using numerical models, experiments, and crystal textures. This work aims to complement the volatile evolution history with two petrological tools based on time-dependent chemical reactions: volatile diffusion across olivine-hosted embayments and concentration gradients of H+ in olivine crystals. 3) Do high-intensity mafic eruptions display a correlation between decompression rate and eruption magnitude?

Current data suggest low and mildly explosive basaltic eruptions show a clear positive correlation between decompression rate and eruption magnitude. However, these data are not available for higher-magnitude eruptions. This project will answer this question with new decompression rates studies supplemented with literature data.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.