A Lot of Hot Air: Degassing and Volcanic Eruptions

Speaker – Marie Edmonds, University of Cambridge

The talk will be given twice on this date, once at 3pm and once at 6pm – please note that if you would like to attend the talk, the 3pm matinee generally has more availability. The talks will be exactly the same in the afternoon and evening.

Programme – 3pm talk
14.30 Tea & Coffee
15.00 Lecture begins
16.00 Event ends

Programme – 6pm talk
17.30 Tea & Coffee
18.00 Lecture begins
19.00 Short drinks reception
20.00 Event ends

Abstract

Volcanism is one of Earth's most spectacular phenomena and it poses significant hazards to our society. Volcanic eruptions may take many forms, ranging from fluid lava flows to ash-rich explosive columns and pyroclastic flows.

As well as silicate melt, volcanoes erupt gas, and it is this volatile phase that is the engine of volcanic eruptions. The exsolution of gases lowers magma density during its ascent through the crust and influences buoyancy as well as its rheological properties. How fast the magma ascends, the formation of bubbles and how efficiently the melt and gas can segregrate from one another in the volcanic conduit largely determines the style of the volcanic eruption at the surface.

This lecture will examine the process of magma degassing and volcanic eruptions using observations from large scales using satellite-based instruments, down to the microscopic scale using observations of crystals and melt in the erupted rocks. A variety of eruption types and tectonic settings will be considered, which together illustrate some of the most dramatic aspects of volcanism. The implications of such emissions of gases for atmospheric chemistry and climate will be discussed, both in recent times and in the geological past.

Biography

Marie Edmonds is a geologist, geochemist and igneous petrologist, and is currently a lecturer at the Earth Sciences Department at the University of Cambridge. She has worked extensively on magma degassing problems in many different volcanic settings, such as the Soufriere Hills Volcano, Montserrat, an eruption ongoing since 1995, and then as a Mendenhall postdoctoral Fellow with the United States Geological Survey based at the Hawaiian Volcano Observatory, before returning to Cambridge in 2006. She has a BA and PhD from the University of Cambridge.