Throw distribution across the Dabbahu−Manda Hararo dike-induced fault array: Implications for rifting and faulting

Dike intrusion and formation of overlying dike-induced normal faults facilitate plate extension. The kinematics of these dike-induced normal faults provide an accessible record of subsurface diking. Here, we use high-resolution light detection and ranging (LiDAR) and interferometric synthetic aperture radar (InSAR) data to explore how strain was distributed across a preexisting dike-induced fault array during diking events in the Dabbahu−Manda Hararo magmatic segment (Afar, Ethiopia) in 2008 and 2010. By analyzing throw of the dike-induced normal faults, we show that only a small number of faults were reactivated during each diking event; the distribution of this reactivation likely reflects dike depth, opening, and inclination, as well as fault orientation. We also show fault throw favorably accrued toward fault centers, away from areas of soft- or hard-linkage. Our high-resolution data sets demonstrate the importance of reactivation to rifting, as it means extension can occur at lower extensional forces, and that fault slip (and seismic hazard) may not localize at sites of fault linkage.