Stress transfer between thirteen successive dyke intrusions in Ethiopia

Stress transfer from a large earthquake may trigger subsequent earthquakes in nearby regions(1-3). Such a mechanism has been suggested for a few isolated cases of magmatic intrusions and eruptions(4-6), but has not been systematically demonstrated. An ongoing rifting episode, which began in 2005, along the Nubia-Arabia plate boundary provides a unique opportunity to test any such linkage. The intrusion of a 60-km-long magmatic dyke marked the beginning of the episode(7-12) and, between June 2006 and July 2009, 12 more dykes were emplaced(13). Here we use geodetic surveys and simple dislocation models to locate and quantify the extension that occurred during each event. We identify regions where tensile stress was increased (unclamped) by the previous dyke intrusions. Of the 12 events that followed the initial intrusion, nine dykes were observed to have at least half of their opening in regions unclamped by the previous events. We propose that the transfer of stress links the 13 dyke intrusion events. We suggest that the stress change that is induced by a new dyke is an important factor in determining the location of future events and could help improve volcanic hazard analysis.