Rift volcanism: past, present and future

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Geosciences

Abstract

Early explorers called it Africa's Great Rift Valley, a narrow strip that runs for thousands of kilometres from Djibouti to Mozambique and is perhaps most famous for the vast herds of the Serengeti, mountain gorillas and dramatic landscapes of high peaks and fertile plains. The mountains and valleys are the signs of a continent slowly tearing apart. Moving apart more slowly than your finger nails grow, the African continent will one day split into two, creating a new ocean. As the Earth's crust stretches and thins - like plasticine when you pull it - rocks melt, and the resulting magma rises to the surface. The resultant eruptions have had a dramatic and varied impact on the landscape: great lakes have filled the holes left by enormous eruptions; eruptions of volcanic glass have created a chain of peaks, and wide fields are filled with scattered cones and lava flows. This volcanic landscape is hazardous - a recent report for the World Bank ranked 49 of Ethiopia's 65 volcanoes in the highest category of hazard uncertainty. The high temperatures associated with magma in the Rift Valley make it a rich source of carbon-neutral geothermal power. Multi-billion dollar investments by development agencies are driving a ten-fold expansion in the geothermal infrastructure in East Africa over the next decade.

However, the majority of scientific research has focussed on volcanoes in other tectonic settings, such as Hawaii and Japan, leaving the volcanoes of the East African Rift largely a mystery. For many of them, we can't even say when the last eruption look place and there is no monitoring equipment to detect the early stages of an upcoming eruption. The eruption of Nabro volcano in 2011 was a timely reminder of the potential threats. Situated on the frontier between Ethiopia and Eritrea, the area is remote and sparsely populated, yet the eruption caused 32 fatalities, displaced >5000 people and disrupted regional aviation. Had this eruption originated from one of other 29 volcanoes with the same perceived hazard, but in densely-populated central Ethiopia, the humanitarian and societal cost would have been considerable.

RiftVolc will focus on the volcanoes of the Main Ethiopian Rift in central Ethiopia. The aim is to understand their past behaviour, look for subtle signs of present-day activity and assess the threat posed to the infrastructure and people on and around them. RiftVolc will involve scientists from many disciplines working together to produce an integrated view of the past, present and future of the volcanoes in this region and compare it to other parts of East Africa and volcanoes elsewhere. Together we will spend several months out in Ethiopia, collecting samples, mapping the geology and deploying geophysical instruments, before returning to the lab to use analyse the data and create computer models of the results. Petrologists and geochemists will look at the lavas and ash to figure out the timing, size and style of past eruptions. Geophysicists will look for tiny earthquakes, changes in gravity, the passage of electrical currents and movements of the Earth's surface to understand the plumbing system feeding the volcanoes today. Finally, experts in hazard assessment will model possible scenarios and create a long-range eruption forecast for Ethiopia. We will work with our colleagues in the University of Addis Ababa and the Geological Survey of Ethiopia to ensure our findings are appropriate communicated to the government, industry and people of Ethiopia and with international groups such as the Global Volcano Model to communicate our results to development agencies such as the UN and the World Bank.

Planned Impact

Beneficiaries
National Government (Devolved Government & Government Agencies)
- The Institute of Geophysics, Space Science and Astronomy (IGSSA) at Addis Ababa University is the national organisation providing geophysical monitoring data and advice during unrest and eruptions, and the School of Earth Sciences advises on the character of past eruptions. There are no trained volcanologists in Ethiopia so they collectively provide scientific advice to the Ministry of Agriculture's Disaster Risk Management and Food Security Sector (DRMFSS), the Civil Aviation Authority and Ethiopian Pilots Association during an eruption.
- The Geological Survey of Ethiopia's geoscience data, advice and services contributes to the sustainable development of the agricultural, industrial, infrastructure and other sectors of the Ethiopian economy.
International Organisations and Agencies.
- The IAVCEI Commission on Hazards and Risk links academic research to decision-makers, to reduce the impact of volcanic hazards.
- The Global Volcano Model (GVM) is an international network creating an information platform on volcanic hazard and risk, and is responsible for the volcano component of the biennial UN Global Assessment Report on Disaster Risk Reduction.
Commercial Sector (Public and Private Geothermal Energy)
- Reykjavik Geothermal Limited develops high enthalpy geothermal resources and will construct Africa's largest (1 GW, $4billion) geothermal power plant in our study area.
- Ethiopian Electrical Power Corporation (EEPCO) currently operates a 7MW geothermal power station in our study area, which they are expanding to 70MW.

We will deliver benefit by:
National Government
- Assist Ethiopian scientific partners to build institutional capacity and a volcano monitoring strategy for observations of, and response to, future unrest and eruptions based on information on past eruptions, the processes driving current unrest, and priorities for potential impacts. Enable IGSSA to establish real-time seismic and geodetic monitoring.
- With in-country partners involved in science advice, monitoring, aviation, national and regional administration, and civil protection, ensure our research responds to the needs of all sectors, and make recommendations for the future.
- Research outputs and methodologies supporting effective decision-making under conditions of uncertainty will assist with policy development to strengthen the resilience of people and assets exposed to volcanic hazards. Deliver to local stakeholders advice and a legacy of tools that are practical for use in a developing, low technology nation to determine optimum mitigation and resilience strategies, supporting Ethiopia's national response to the Hyogo Framework for Action international policy for disaster risk reduction. Enable DRMFSS to incorporate volcanic hazards into the local disaster risk profiling exercise.
International Organisations and Agencies
- Through organisations such as the GVM and IAVCEI commission, disseminate our results, share experience and practice applicable in a developing nation, and consult over the development of methodologies to underpin future global-scale analyses of volcanic risk.
- Transfer knowledge and contribute to policy through interaction with the UK Cabinet Office Civil Contingencies Secretariat and input to the National Risk Register.
Commercial Sector
- Collaborate with Rekjavik Geothermal and EEPCO to exchange data that inform geothermal exploration and production, and incorporate hazard analyses specific to rift volcanism to mitigate against potential future economic losses resulting from volcanic activity.

Activities detailed in the Pathways to Impact document will improve monitoring for early warning, facilitate science into policy supporting planning to build resilience, contribute to global data sets and volcanic risk modelling, increase the resilience of industry to support economic development, and facilitate better communities.

Publications


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Gallacher Ryan J. (2016) The initiation of segmented buoyancy-driven melting during continental breakup in NATURE COMMUNICATIONS


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Goitom B (2015) First recorded eruption of Nabro volcano, Eritrea, 2011. in Bulletin of volcanology

 
Description Electrical conductivity is not high beneath Aluto volcano. We would expect to see high electrical conductivity because other techniques suggest there is a magma chamber underlying the volcano. The lack of enhanced electrical conductivity suggests there is not well-connected melt, and may have implications for the chemical composition of the melt. Aluto is the site of a geothermal energy plant that is currently undergoing expansion. We do, however, find a zone of high conductivity beneath the rift flanks to the north-west of Aluto, suggesting there is melt storage there.
Exploitation Route Joint interpretation with other techniques, particularly of sub-surface beneath Aluto volcano, should better identify the nature of the magma chamber there.
Sectors Energy
 
Description Data collected in 2016 are being analysed to help recommend sites for boreholes in drought-stricken areas of Ethiopia
First Year Of Impact 2016
Sector Agriculture, Food and Drink
Impact Types Societal,Economic