Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

A mantle magma reservoir beneath an incipient mid-ocean ridge in Afar, Ethiopia

This article has been updated


Shallow magma reservoirs exist in the crust beneath volcanoes and mid-ocean ridges, yet there are no reports of extensive magma bodies within the uppermost mantle. Indeed the buoyancy of magma should cause it to intrude into the crust, preventing it from ponding in the mantle below. The Dabbahu magmatic segment in Afar, Ethiopia, marks the late stages of continental rifting. This segment has been active since 2005 and has experienced repeated magma intrusions1,2,3,4,5,6. Here we use magnetotelluric data to image magma bodies beneath it. We identify a 30-km-wide region of very high electrical conductivity that reaches down to about 35 km depth. We interpret this region as a large volume of magma of at least 500 km3 that extends well into the mantle and contains about 13% melt fraction. The magma volume is orders of magnitude larger than that intruded during a typical rifting episode, implying that the magma reservoir persists for several tens of thousands of years. This is in marked contrast to the situation beneath mid-ocean ridges, where melt supply is thought to be episodic7,8,9,10,11. Large magma reservoirs within the mantle may therefore be responsible for the localization of strain that accompanies the final stages of continental break-up.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Tectonic setting of the area and magnetotelluric site distribution.
Figure 2: Data pseudo-sections and their predictions by the preferred model.
Figure 3: Preferred 2D resistivity model beneath the profile from joint inversion of the transverse electric and transverse magnetic mode data.

Similar content being viewed by others

Change history

  • 06 September 2013

    In the version of this Letter originally published online, the published online date should have read '5 September 2013'. This has been corrected in the PDF and HTML versions of the Letter.


  1. Wright, T. J. et al. Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature 442, 291–294 (2006).

    Article  Google Scholar 

  2. Rowland, J. V. et al. Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode Afar. Geophys. J. Int. 171, 1226–1246 (2007).

    Article  Google Scholar 

  3. Keir, D. et al. Evidence for focused magmatic accretion at segment centers from lateral dike injections captured beneath the Red Sea rift in Afar. Geology 37, 59–62 (2009).

    Article  Google Scholar 

  4. Ebinger, C. J. et al. Capturing magma intrusion and faulting processes during continental rupture: Seismicity of the Dabbahu (Afar) rift. Geophys. J. Int. 174, 1138–1152 (2008).

    Article  Google Scholar 

  5. Hamling, I. J., Ayele, A., Bennati, L., Calais, E. & Ebinger, C. J. Geodetic observations of the ongoing Dabbahu rifting episode: New dyke intrusions in 2006 and 2007. Geophys. J. Int. 178, 989–1003 (2009).

    Article  Google Scholar 

  6. Grandin, R. et al. Transient rift opening in response to multiple dike injections in the Manda Hararo rift (Afar, Ethiopia) imaged by time-dependent elastic inversion of interferometric synthetic aperture radar data. J. Geophys. Res. 115, B09403 (2010).

    Google Scholar 

  7. Key, K., Constable, S., Liu, L. & Pommier, A. Electrical image of passive upwelling beneath the northern East Pacific Rise. Nature 495, 499–502 (2013).

    Article  Google Scholar 

  8. Canales, J. P., Collins, J. A., Escartı´n, J. & Detrick, R. S. Seismic structure across the rift valley of the Mid-Atlantic Ridge at 23° 20’ (MARK area): Implications for crustal accretion processes at slow spreading ridges. J. Geophys. Res. 105, 28411–28425 (2000).

    Article  Google Scholar 

  9. MacGregor, L. M., Constable, S. & Sinha, M. C. The RAMESSES experiment–III. Controlled-source electromagnetic sounding of the Reykjanes Ridge at 57° 45′N. Geophys. J. Int. 135, 773–789 (1998).

    Article  Google Scholar 

  10. Singh, S. C. et al. Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field. Nature 442, 1029–1032 (2006).

    Article  Google Scholar 

  11. Heinson, G., Constable, S. & White, A. Episodic melt transport at mid-ocean ridges inferred from magnetotelluric sounding. Geophys. Res. Lett. 27, 2317–2320 (2000).

    Article  Google Scholar 

  12. Roberts, J. J. & Tyburczy, J. A. Partial-melt electrical conductivity: Influence of melt composition. J. Geophys. Res. 104, 7055–7065 (1999).

    Article  Google Scholar 

  13. Sternberg, B., Washburne, J. C. & Pellerin, L. Correction for the static shift in magnetotellurics using transient electromagnetic soundings. Geophysics 53, 1459–1468 (1988).

    Article  Google Scholar 

  14. Simpson, F. & Bahr, K. Practical Magnetotellurics (Cambridge Univ. Press, 2005).

    Book  Google Scholar 

  15. Caldwell, T. G., Bibby, H. M. & Brown, C. The magnetotelluric phase tensor. Geophys. J. Int. 158, 457–469 (2004).

    Article  Google Scholar 

  16. McNeice, G. W. & Jones, A. G. Multisite, multifrequency tensor decomposition of magnetotelluric data. Geophysics 66, 158–173 (2001).

    Article  Google Scholar 

  17. Siripunvaraporn, W. & Egbert, G. An efficient data sub-space inversion method for 2-D magnetotelluric data. Geophysics 65, 791–803 (2000).

    Article  Google Scholar 

  18. Hammond, J. O. S. et al. The nature of the crust beneath the Afar triple junction: Evidence from receiver functions. Geochem. Geophys. Geosys. 12, Q12004 (2011).

    Article  Google Scholar 

  19. Cornwell, D. G., Maguire, P. K. H., England, R. W. & Stuart, G. W. Imaging detailed crustal structure and magmatic intrusion across the Ethiopian Rift using a dense linear broadband array. Geochem. Geophys. Geosys. 11, Q0AB03 (2010).

    Article  Google Scholar 

  20. Nooner, S. L. et al. Post-rifting relaxation in the Afar region, Ethiopia. Geophys. Res. Lett. 36, L21308 (2009).

    Article  Google Scholar 

  21. Guidarelli, M. et al. Surface wave tomography across Afar, Ethiopia: Crustal structure at a rift triple-junction zone. Geophys. Res. Lett. 38, L24313 (2011).

    Article  Google Scholar 

  22. Stork, A. et al. Uppermost mantle (P n) velocity model for the Afar region, Ethiopia: An insight into rifting processes. Geophys. J. Int. 193, 321–328 (2013).

    Article  Google Scholar 

  23. Kendall, J. M., Stuart, G. W., Ebinger, C. J., Bastow, I. D. & Keir, D. Magma-assisted rifting in Ethiopia. Nature 433, 146–148 (2005).

    Article  Google Scholar 

  24. Keir, D. et al. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression. Nature Commun. 2, 285 (2011).

    Article  Google Scholar 

  25. Hashin, Z. & Shtrikman, S. A. variational approach to the theory of the effective magnetic permeability of multiphase materials. J. Appl. Phys. 33, 3125–3131 (1962).

    Article  Google Scholar 

  26. Li, S. et al. Partial melt or aqueous fluid in the mid-crust of Southern Tibet? Constraints from INDEPTH magnetotelluric data. Geophys. J. Int. 153, 289–304 (2003).

    Article  Google Scholar 

  27. Pommier, A. & Le Trong, E. SIGMELTS: A web portal for electrical conductivity calculations in geosciences. Comput. Geosci. 37, 1450–1459 (2011).

    Article  Google Scholar 

  28. Baba, K., Chave, A. D., Evans, R. L., Hirth, G. & Mackie, R. L. Mantle dynamics beneath the East Pacific Rise at 17°S: Insights from the Mantle Electromagnetic and Tomography (MELT) experiment. J. Geophys. Res. 111, B02101 (2006).

    Google Scholar 

  29. Hayward, N. & Ebinger, C. Variations in along-axis segmentation of the Afar Rift System. Tectonics 15, 244–257 (1996).

    Article  Google Scholar 

  30. Belachew, M. et al. Comparison of dike intrusions in an incipient seafloor-spreading segment in Afar, Ethiopia: Seismicity perspectives. J. Geophys. Res. 116, B06405 (2011).

    Article  Google Scholar 

Download references


This research has been supported financially by NERC (grant NE/E007147/1 and PhD studentship for N.E.J.), the School of GeoSciences (MSc by Research MTEM Partial Scholarship to M.D.), CNRS (financial support for S.H.), and in-kind by equipment loans from the NERC Geophysical Equipment Facility (GEFSC loans 855 and 907), and the Geophysical Instrument Pool Potsdam (part of GeoForschungsZentrum) through the auspices of O. Ritter and U. Kalberkamp (BGR, Hannover). The Institute for Geophysics, Space Science and Astronomy, Addis Ababa University and the Geological Survey of Ethiopia are thanked for logistical support, as is Y. Lemma for help with the fieldwork. Helicopter access to the rift was provided by C. Stewart, Everett Aviation. We also acknowledge discussions with and results in advance of publication from Afar Rift Consortium colleagues and Project Partners, in the UK, Ethiopia, USA and New Zealand.

Author information

Authors and Affiliations



All authors participated in the fieldwork. M.D., S.H. and N.E.J. processed the data. M.D. and N.E.J. analysed their dimensionality and corrected for galvanic distortion. M.D., N.E.J. and S.F. performed 2D inversions. G.J.K.D. designed and constructed the data recording systems. K.A.W., S.H. and N.E.J. undertook most of the model interpretation, including estimating melt fractions and volumes. K.A.W. obtained the financial support, and wrote the article (with comments from co-authors).

Corresponding author

Correspondence to K. A. Whaler.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 4339 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Desissa, M., Johnson, N., Whaler, K. et al. A mantle magma reservoir beneath an incipient mid-ocean ridge in Afar, Ethiopia. Nature Geosci 6, 861–865 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing