|Region:||Africa and Red Sea|
|Measurement method(s):||InSAR, GPS - campaign|
|Duration of observation:||May 2005 - October 2005|
|Inferred cause of deformation:||Magmatic|
|Characteristics of deformation:|
In 2005 a 60 km dyke, with 8 m opening, connecting the Manda Hararo and Dabbahu regions occured (Wright et al. 2012). Following the 2005 dyke intrusion 12 more dykes occured at Manda Hararo, and are discussed seperately on the Manda Hararo page. Wright et al. (2006) report that magma was injected along the 2005 dyke between depths of 2 and 9 km, corresponding to a total intrusion volume of 2.5 km3. Wright et al. (2006) also present a 3D deformation field for the Dabbahu rifting episode derived from satellite radar data. The deformation field showsthat the entire segment ruptured, making it the largest to have occurred on land in the era of satellite geodesy. They report that much of the magma appears to have originated from shallow chambers beneath Dabbahu and Gabho volcanoes to the north, where an explosive fissural eruption occurred on 26 September 2005.
Gradin et al. (2009) provides an alternative InSAR study. They report on the geometry of the dike and neighboring magma chambers and perform an inversion for the distribution of opening of the dike, as well as slip on rift border faults. Above the dike the find faults slip by an average 3 m, yielding an estimated geodetic moment of 3.5 × 1019 Nm. The conclude that Dabbahu was two-stage intrusion, whereby rifting in the northern Manda Hararo Rift was triggered by magma upwelling in the Dabbahu area, at the northern extremity of the magmatic segment.
One study (Hamling et al. 2009), using InSAR and GPS, report no subsidence at either of the volcanoes at the northern end of the segment, which partly fed the 2005 September dyke, during the 2007 5 km dyke. Pagli et al. (2014) have also looked at the 2007 dyke intrusion. Their results agree with the other studies.
|Reference:||Wright, T. J., Ebinger, C., Biggs, J., Ayele, A., Yirgu, G., Keir, D., & Stork, A. (2006). Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature, 442(7100), 291-294.|
|Reference:||Grandin, R., A. Socquet, R. Binet, Yann Klinger, E. Jacques, J‐B. de Chabalier, G. C. P. King (2009). September 2005 Manda Hararo‐Dabbahu rifting event, Afar (Ethiopia): constraints provided by geodetic data. Journal of Geophysical Research: Solid Earth (1978–2012) 114.|
|Reference:||Hamling, Ian J., Atalay Ayele, Laura Bennati, Eric Calais, Cynthia J. Ebinger, Derek Keir, Elias Lewi, Tim J. Wright, and Gezahegn Yirgu. 2009. Geodetic observations of the ongoing Dabbahu rifting episode: new dyke intrusions in 2006 and 2007. Geophysical Journal International 178. 989-1003.|
|Reference:||NASA Landsat image, 1999|
|Reference:||Pagli, C. et al., 2014. Current plate boundary deformation of the Afar rift from a 3-D velocity field inversion of InSAR and GPS. Journal of Geophysical Research: Solid Earth, 119(11), pp. 8562-8575.|
Field photograph of the surface expression of the Dabbahu 2005 dyke intrusion. Note people (on left) for scale. Photo by Anthony Philpotts, 2005 (University of Connecticut).
The Dabbahu volcanic massif is in the center of this image. The dyking discussed in this report extend towards the SSE. (NASA, landsat 1999).