Under the faultlines

volcano erupting

Volcanic eruptions grab all the headlines, but it is hard to know when or where they will occur. Unravelling how sheets of magma, called dykes, form underground and affect the Earth's surface may provide the answer.

29 August 2018 by Craig Magee

As part of a series of interviews with new NERC Independent Research Fellows, Craig Magee tells us about the portability of being a fellow and why he's going underground to uncover the science behind volcanic eruptions.

For me, the appeal of the NERC Independent Research Fellowship (IRF) was its flexibility and portability, which meant that should I move to another university, I could take the grant with me. The five-year length of the fellowship also meant that I could develop an ambitious project plan.

Prior to being awarded the NERC IRF, I completed my undergraduate degree and PhD at the University of Birmingham in 2011. Since then I've been at Imperial College London, first as a postdoctoral research associate, before beginning a junior research fellowship with the university.

My research will focus on understanding what happens underground before a volcanic eruption. That might help us better understand how continents break up over time and perhaps get more of a warning of when a volcanic eruption might happen. To do this, I will be looking at the role that a geological feature called a 'dyke' plays in the process.

Although volcanoes grab all the headlines, many volcanic eruptions are accompanied by the formation of dykes beneath the Earth's surface. Dykes are formed when upwelling magma (molten rock) is forced into a pre-existing crack in the rock, which then solidifies and forms a vertical sheet. These can fracture and push apart the surrounding rock, producing small earthquakes, and, if magma injection continues, can cause these fractures to develop into faults (where rock on one side of the crack starts to slip past the other). These dykes and dyke-induced faults can cause the break-up of continents and so play a major role in shaping the volcanic and tectonic history of the planet.

Craig Magee

Craig Magee

To understand how dykes and dyke-induced faults control volcanic, tectonic and planetary processes, we need to understand how faults grow above dykes. However, because most dykes are formed deep underground, their formation cannot be directly observed and is rarely captured using the geophysical techniques scientists have and use.

Many computer simulations have been employed to try to replicate fault growth above dykes, but without being able to examine the three-dimensional structure of natural dykes and dyke-induced faults, the simulations cannot be tested.

I have used seismic reflection data, which gives us 3D X-ray-like subsurface images, to identify the first swarm of ancient dykes and dyke-induced faults from the northwest margins of the Australian continent. This data will allow me to study their 3D structure and test formation predictions made by computer models. Using another type of high definition imaging called 'lidar', I will also study dyke-induced faults in Ethiopia where, unlike Australia, these processes are still active.

Results from these analyses will allow me to design new simulations that will replicate the processes in 3D and reveal the role dyke-induced faults play in the break-up of continents, whether they influence the evolution of continental margins (where most of the planet's oil and gas reserves reside), and even how they might allow us to predict future volcanic eruptions.

The NERC IRF scheme is designed to develop scientific leadership among the most promising early-career environmental scientists, by giving all fellows five years' support, which will allow them sufficient time to develop their research programmes and to gain international recognition.

Applications for the current Independent Research Fellowship call closes on 2 October 2018. Further information can be found on the Independent Research Fellowship webpage.