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Book Chapter

Seismicity of the central Afar rift and implications for Tendaho dam hazards

By
Atalay Ayele
Atalay Ayele
1
Institute of Geophysics Space Science and Astronomy, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
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Cynthia J. Ebinger
Cynthia J. Ebinger
2
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA
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Carolyn Van Alstyne
Carolyn Van Alstyne
2
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA
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Derek Keir
Derek Keir
3
Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton SO14 3ZH, UK
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Casey W. Nixon
Casey W. Nixon
3
Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton SO14 3ZH, UK
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Manahloh Belachew
Manahloh Belachew
2
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA
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James O. S. Hammond
James O. S. Hammond
4
Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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Published:
January 01, 2016

Abstract

Temporary broadband seismic networks deployed from 2007 to 2011 around the Afar triple junction of the East African Rift System provide insights into seismicity patterns of the actively deforming crust around the 1.86 km3 impounded lake system behind the Tendaho dam. The observed seismicity correlates well with the active magmatic centres around central Afar. The area around the dam site is characterized by a network of intersecting NNE- and NW-trending faults. Seismicity clusters observed in the specified time interval indicate that both fault sets are active and are potential sources of seismogenic hazards. The dam neighbourhood is naturally active and it is a challenge to associate the observed seismic activity to either a change in magmato-tectonic conditions or attribute it to the influence of reservoir load. It is evident that the dam region experiences high levels of seismic and volcano-tectonic unrest, regardless of the origin of the activity. The spatial overlap of narrow zones of crustal seismicity and upper mantle low velocity zones observed in S-wave tomography models suggests that melt production zones guide the distribution of strain during continental rupture. Given its volcanically and seismically active setting, the Tendaho dam site and the surrounding region require continuous monitoring for the safety of downstream populations and development infrastructures in the Afar National Regional State of Ethiopia.

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Contents

Geological Society, London, Special Publications

Magmatic Rifting and Active Volcanism

T. J. Wright
T. J. Wright
University of Leeds, UK
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A. Ayele
A. Ayele
Addis Ababa University, Ethiopia
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D. J. Ferguson
D. J. Ferguson
University of Leeds, UK
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T. Kidane
T. Kidane
Addis Ababa University, Ethiopia
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C. Vye-Brown
C. Vye-Brown
British Geological Survey, UK
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Geological Society of London
Volume
420
ISBN electronic:
9781862391345
Publication date:
January 01, 2016

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