Observing Oblique Slip During Rift Linkage in Northern Afar

Extensional plate boundaries are segmented by offsets that transfer extension between the ends of adjacent portions of the rift by linkage zones ranging in width from a few tens of kilometers to several hundreds of kilometers. However, the kinematics of linkage zones is poorly constrained as direct observations are difficult to make. Here we combine InSAR, seismicity, and structural geology data from the Afar rift to show that an active linkage zone currently connects the two offset Erta Ale and Tat Ali segments. The overall right-lateral shear between the segments is accommodated primarily by oblique left-lateral slip along faults subparallel to the rift segments but an active conjugate fault system with right-lateral slip is also present. Our results provide the first direct observational evidence that offset rift segments during continental breakup can be linked by a shear zone composed of a conjugate set of oblique slip faults.