Afar Rift project — geological mapping

BGS international work

Afar is part of the volcanically and seismically active portion of the African Rift and is one of the few places on Earth where we can witness plate divergence as the continental crust splits apart to form a new ocean.

The Afar Rift project tracked the creation of magma (molten rock) from deep within the Earth, studying how it migrates and evolves as it rises towards the surface.

We investigated how the surface of the Earth reacts as it is thinned and split apart, and how the magma is intruded into this thin crust to form the beginnings of a new ocean.

Afar Rift Consortium

A BGS team are mapping the geology of the Afar desert in northern Ethiopia — reputed to be the hottest place on Earth.

Between 2007 and 2012, BGS were project partners with the Afar Rift Consortium (ARC), which comprises Leeds, Bristol, Oxford, Cambridge and Edinburgh universities and has links with scientists in the US, Ethiopia, France and New Zealand.

The ARC was an extensive multidisciplinary research group investigating:

  • where magmatic bodies form and pond
  • the geochemical composition and evolution of magmas
  • the timescales over which these processes occur
  • how magma moves in areas of lithospheric extension

Led by Charlotte Vye-Brown, BGS's role in this research was to conduct geological mapping of the Afar region, encompassing all the active research areas, to provide an overview of the stratigraphy and the changes in style, location and composition of volcanism with time. The project utilised interpretations of remote sensing data to support ground-based fieldwork in this unique natural laboratory.

Rapid mapping techniques

Airborne and satellite remote sensing provide a useful technique for rapid mapping in terrain that is inaccessible to conventional fieldwork. Remote sensing is the technique of measuring spectral reflectance and emittance from the Earth's surface using sensors mounted on airborne or spaceborne platforms.

These measurements are used to infer the nature and characteristics of the land at the time of observation by comparing the image spectral response patterns with reference spectra of known surface materials.

Using colour to analyse the rocks

Geological materials have characteristic absorption features at particular wavelengths, and as long as there is sufficient spectral detail then image analyses can be performed to provide an interpretation of the exposed geological materials.

Landsat ETM+ data have been acquired and processed for the Afar region. After initial removal of haze effects and data conversion, the FLAASH atmospheric correction algorithm was applied to provide a measure of ground reflectance for each image pixel. These were then compared to spectral reflectance curves of known geological materials to provide an interpretation of the geology within the region. Field observation is then focussed on particular areas to verify the accuracy in image interpretation, thus allowing vast areas to be mapped rapidly and reducing the time and effort spent on conventional fieldwork.


BGS are continuing their work in this region through the RiftVolc Project. Please see the project pages for more information and contact details.

2008 expedition gallery