Active Development of Continental Rifts: Wide Swath Interferometry in East Africa.

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences

Abstract

We like to think of the ground as a solid, immovable platform in an uncertain world, but even the continents are slowly drifting beneath our feet; the patterns of land and sea constantly changing. East Africa is being gradually pulled apart by the forces of plate tectonics - eventually there will be a new ocean, but at the present day, we can already see the beginnings: the three thousand kilometre long Great Rift Valley containing a string of volcanoes and prone to earthquakes. But what happens next? The established view is that stretching takes place during earthquakes as two blocks slide past each other on faults. Yet recent satellite observations have shown that magma is important. Imagine sliding apart two pieces of wood stacked on top of each other - the forces of friction resist you. Now imagine the pieces of wood are floating on a pond: this is a much easier task, there is less friction and the water flows to fill the gap. This is similar to what happens in East Africa - the presence of magma alters the way in which the continent stretches. Scientists are working on a new paradigm, one in which magma plays a crucial role in continental rifts. Before new models can be developed, we need a clear set of observations against which to test them. Currently only a few case studies are available - yet we need to see the patterns of magma and fault movement throughout the rift: Is the stretching focused on the faults or near the volcanoes the centre of the valley? How much magma is there? Magma rises in short pulses, like drips, but what controls how these drips form? The best way to begin answering these questions is to use satellite observations - avoiding the need for time-consuming expeditions to remote and dangerous terrain. Using satellite-based radar, it is possible to cover hundreds of kilometres of the rift with a single image and detect small amounts of uplift or subsidence associated with stretching and magma moving underground. Once particular areas of concern have been identified, ground-based instruments can be used to provide more detailed observations on individual examples. Using the archive of large satellite images, I will analyse ground movement spanning 7 years and covering the length of the rift, from Ethiopia to Malawi. These observations will describe the pattern of faulting and magma movement in space and time, allowing the development of a new class of continental rifting models, to include the effects of magma. In addition to these scientific goals, this project will generate information on what is currently an underestimated source of potential hazard and we will communicate the results to local and global management bodies.
 
Description The findings have demonstrated that deformation is widespread at volcanoes within the East African Rift with significant implications for volcanic hazard and the rapidly-expanding geothermal industry. It has also raised questions about the interpretation of volcano deformation on a global scale, and the provision of satellite data to the developing world.
Exploitation Route This grant has inspired further funding from numerous sources (see further funding information)
Sectors Energy,Environment,Government, Democracy and Justice
 
Description The findings have demonstrated that deformation is widespread at volcanoes within the East African Rift with significant implications for volcanic hazard and the rapidly-expanding geothermal industry. It has also raised questions about the interpretation of volcano deformation on a global scale, and the provision of satellite data to the developing world.
First Year Of Impact 2012
Sector Energy,Environment
Impact Types Economic
 
Description Exploring Global Patterns of Volcanic Deformation with Satellite Radar.
Amount £15,000 (GBP)
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 04/2013 
End 04/2014
 
Description NERC GEF Equipment Loan
Amount £81,000 (GBP)
Funding ID 992 
Organisation UK Research Council 
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 03/2013 
End 04/2014
 
Description NERC GEF Equipment Loan
Amount £81,000 (GBP)
Funding ID 992 
Organisation UK Research Council 
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 03/2013 
End 03/2015
 
Description RiftVolc (NERC Large Grant)
Amount £584,072 (GBP)
Funding ID NE/L01372X/1 
Organisation Natural Environment Research Council (NERC) 
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 09/2014 
End 09/2019
 
Description IGSSA 
Organisation Addis Ababa University
Department Institute of Geophysics, Space Science and Astronomy (IGSSA)
Country Ethiopia, Federal Democratic Republic of 
Sector Academic/University 
PI Contribution Co-organised field programmes and import/export of equipment. Spent 1 month teaching a course on InSAR for MSc students. Co-supervised a MSc research project. Joint interpretation of scientific results
Collaborator Contribution Co-organised field programmes and import/export of equipment. Local knowledge (including both scientific knowledge of rift tectonics, techniques such as GPS and logistics) Joint interpretation of scientific results
Impact Joint publications Joint funding
Start Year 2012
 
Description University of Nairobi 
Organisation University of Nairobi
Country Kenya, Republic of 
Sector Academic/University 
PI Contribution Co-organised a field campaign and sample export
Collaborator Contribution Co-organised a field campaign and sample export Arranged meetings with Ministry of Mines
Impact Joint publications
Start Year 2012
 
Description InSAR course for MSc Geodesy Class at Addis Ababa University 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A one-month intensive course on using InSAR to students on an MSc in Geodesy programme at Addis Ababa University.

The participants have gone back to their respective countries in East Africa and several continue to use InSAR, and several remain in contact.
Year(s) Of Engagement Activity 2012
 
Description New Scientist Article 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Article inspired by a talk given at the Royal Astronomical Society, and based on further interviews.
Year(s) Of Engagement Activity 2013