Dike-fault interaction during the 2004 Dallol intrusion at the northern edge of the Erta Ale Ridge (Afar, Ethiopia)



[1] During continental rifting the interaction between faulting and magmatic intrusions is not well understood. Using InSAR and seismicity, we show that a ∼0.06 km3 dike was intruded along the Dallol segment, Ethiopia and was accompanied by a Mw 5.5 earthquake and associated fault slip along the western flank of the rift. The intrusion was fed by a previously unidentified magma chamber under Dallol. The total seismic moment release was ∼2.3 × 1017Nm, ∼10% of the geodetic moment. This is a higher proportion than during the 2005–2009 Dabbahu rifting episode, which ranged between 1–4% of the geodetic moment. A larger component of faulting occurs at Dallol than at Dabbahu segment, a feature we interpret to be related to the proximity (10 km) of the Dallol segment to the rift margin, where well-developed faults facilitate slip.