How does the Earth's crust grow at divergent plate boundaries? A unique opportunity in Afar, Ethiopia

Dataset description

The African continent is slowly splitting apart along the East African rift valley, a 3000 km-long series of deep basins and flanking mountain ranges. This process may eventually lead to the formation of a new ocean, but on a time scale of millions of years. In the remote Afar depression in northern Ethiopia, Earth's outermost shell, usually a relatively rigid, 150 km-thick plate, has been stretched, thinned and heated to the point of rupture, to the extent that a new ocean is about to form. Below the surface, upwelling rocks from Earth's mantle below are partially melting, rising, and cooling. Here, we have the unprecedented opportunity to witness the process of plate rupture and upwelling of molten rock (magma). Normally, this process occurs within shallow seas, or along the established seafloor spreading centres deep under the oceans; in Afar, though, we can actually walk across the region as it happens. Satellite observations of the earth show that tectonic plates move apart, on average, very slowly: usually at a few centimetres per year, or about the rate of fingernail growth. Very occasionally, however, sudden large movements occur, often with devastating consequences. In September 2005, a series of fissures opened along a 60 km section of the Afar depression, as the plate responded catastrophically to forces pulling it apart. Over about a week, the rift pulled apart by 8 metres, and dropped down by up to 1 metre. As told by local people, a series of earthquakes signalled the rise of molten rock to the surface on September 26, and ash darkened the air locally for 3 days. At the same time, satellites tracking the region showed that the surface above nearby volcanoes subsided by as much as 3 metres, as magma was injected along the fissure below the surface. The rapidity and immense length of rupture are not unexpected, but have never before been measured directly. The Afar depression is so hot and dry that almost no vegetation obscures the rocks exposed on its top surface; this also means that we can use satellites to image them and to measure the way that the Earth's surface changes as faults move, and as pressurised molten rock moves up and along the length of fissures within the rift valley. In the nine months since the first major earthquakes, more dramatic surface changes have continued to take place, and earthquakes continue to stir the earth. We are proposing a major set of experiments that will bring together experts on Earth deformation, and on magma sources, movement and eruption to this unique natural laboratory. Over the next five years, a team of UK, Ethiopian and US scientists will collaborate to find answers to fundamental questions of plate tectonics: . How do the different layers of the plate stretch apart? . Where does molten rock form and rise to form new oceanic crust? . How does the molten rock move up to the surface? Satellites will image the earth from above, and sensors will record sound waves from distant and near earthquakes and natural magnetic signals to image the thickness of the rock layers the plate comprises, and discover where the magma is located prior to eruption. We will also collect and analyse the composition of rocks from young volcanoes in the same region. The Earth history deduced from compositional variations in space and time will give us clues as to when and how often similar sorts of events happened in the past / and may happen again in the future.

Further information

For more information please contact:


Environmental Science Centre, Nicker Hill, Keyworth
NG12 5GG

Tel : +44 (0)115 936 3143
Fax :+44 (0)115 936 3276


Dataset details

Author(s) Wright, Tim J
Principal Investigator(s) Wright, Tim J
University of Leeds
Language English
Curator British Geological Survey
Supply media/format Not available
Storage format Not available
Frequency of update not applicable
Start of capture {ts '2007-03-01 00:00:00'} Not known
End of capture {ts '2017-09-20 11:32:16'} Not known
Contact details
Department Enquiries
Organisation British Geological Survey
Address Environmental Science Centre, Nicker Hill, Keyworth
City Nottingham
County Nottinghamshire
Country United Kingdom
Postcode NG12 5GG
Telephone +44 (0)115 936 3143
Fax +44 (0)115 936 3276
Topic category code (ISO) geoscientificInformation (information pertaining to earth sciences)
Keyword source BGS Keyphrases
Spatial details
Spatial Reference System Latitude and Longitudes on undefined datum and spheroid []
Dataset extent
Coverage (Lat/Long) North boundary : 15
East boundary  : 44
South boundary : 9
West boundary  : 39
Metadata language English
Metadata last updated 27th May 2011
Metadata standard compliance NERC profile of ISO19115:2003
Copyright and IPR
The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.