Quantitative constraints on faulting and fault slip-rates in the northern Main Ethiopian Rift

The Boset magmatic segment (BMS) of the northern Main Ethiopian Rift (MER) is an ideal natural laboratory to investigate the kinematics, interaction, and rates of activity within a fault network in a magma‐rich rift. In this paper we take advantage of the availability of 1) high‐resolution remote sensing data (LiDAR, Aster); 2) absolute age chronology on offset reference surfaces; 3) well‐exposed active normal fault arrays to place new constraints on rift kinematics and strain distribution, and to quantify the architecture and fault slip‐rates at different temporal scales within a magmatic segment. We found that the rift border faults strike ~NE, while the younger faults in the rift segments strike NNE. Analyses of geometric rift parameters show that the axial active part of the rift is transtensional with an increase of the shear component northward. The fault displacement analyses and displacement: length ratios increase towards the segments tips suggesting a significant contribution of fault growth by linkage. In contrast, magmatism is focused on the segment centre and localized to a narrow zone. Estimated fault slip‐rates vary, with rates of up to ~0.37 mm/yr in ~0.3 Ma old rift floor deposits, whereas higher rates of up to ~4.4 mm/yr are observed for faults cutting through ~6 ka lavas. The difference in slip‐rates indicates short term variability or a very active recent episode compared to long‐term low average slip‐rates