Lots of CO2 seeps out of Ethiopia. No one notices.

By Jonathan Hunt, University of Oxford

Surveys measuring soil gases in Ethiopia suggest that the East African Rift is responsible for a large flux of CO₂ as it seeps out along faults in the Earth’s crust, this has largescale implications for the global carbon cycle and can gives insight into magma storage in the rifting crust. Magma from the mantle carries dissolved CO₂ as it migrates towards the surface. The CO₂ then exsolves out of the melt, travelling along fractures of enhanced permeability. In some places, this release of gas and heat reveals itself in the form of hot springs and fumaroles, but elsewhere the gas percolates through the soil and is released without anyone noticing. Given the large amounts of gas coming out of the rift in Ethiopia, we’re interested in how much magma is stored in the crust. The faults that release gas are around 10 km from the nearest volcano, so it looks like magma could be stored throughout the rift and not just beneath silicic centres.

Jonathan Hunt is a DPhil student at the University of Oxford (jonathan.hunt@univ.ox.ac.uk), supervised by Tamsin Mather and David Pyle. His research is in the ways faults and fractures affect volcanic processes within the Main Ethiopian Rift, and involves satellite imagery, field trips and occasional heat stroke. You can find out more by visiting his website and/or blog: https://www.earth.ox.ac.uk/people/jonathan-hunt/, https://jonathan-hunt.tumblr.com. Read Jonathan’s recent paper on spatially variable CO₂ degassing in the Main Ethiopian Rift here: http://onlinelibrary.wiley.com/doi/10.1002/2017GC006975/full