This dataset contains geological data from the Western Afar Margin (WAM) in East Africa. These in-clude (reprocessed) earthquake data from previously published surveys and publically accessible databases (Keir et al. 2006, 2009; Ebinger et al 2008; Belachew et al. 2011; Illsley-Kemp et al. 2018a, b and the GCMT Project 2019), which form the basis for Seismic Moment Release (SMR) mapping as well as and tectonic stress analysis, revealing the location and intensity of ongoing deformation, as well as the direction of current extension, respectively. In addition, we present various large-scale maps of the WAM, depicting faults, dikes and sedimentary basins as interpreted from topographic indicators.Field data (GPS locations, fault measurements, field book), acquired during two field campaigns in Ethiopia and Eritrea are included, as well as the kinematic interpretation of the field data using Wintensor software (Delvaux & Sperner 2003). These results are combined with previously published kinematic data from Eritrea and Ethiopia (i.e. the northernmost and southern segments of the WAM, studied by Chorowicz et al. 1999 and Sani et al. 2017), yielding the first coherent overview of (current) tectonic deformation covering the whole margin. Note that we also provide a field book with detailed descriptions of every outcrop, including photographs. Finally, we include unique borehole data from the Kobo graben area, based on well logs from irrigation projects kindly provided to us by local geologists during the Ethiopian field campaign (see section 2.5 and the acknowledgements) .Applications and interpretation of the data provided in this dataset can be found in Zwaan et al. (in review). For more description please refer to the data description. This data publication consists of 90 files: (digital) maps, GPS locations, tables, text and Wintensor files. A detailed overview of all files within this dataset is given in the List of Files.
This data set includes images and videos depicting the evolution of deformation and topography of 17 analogue experiments c passive margin development, to better understand the ongoing tectonics along the western margin of Afar, East Africa. The tectonic background that forms the basis for the experimental design is found in Zwaan et al. 2019 and 2020a-b, and references therein. The experiments, in an enhanced gravity field in a large-capacity centrifuge, examined the influence of brittle layer thickness, strength contrast, syn-rift sedimentation and oblique extension on a brittle-viscous system with a strong and weak viscous domain.
All experiments were performed at the Tectonic Modelling Laboratory of of the Istituto di Geoscience e Georisorse - Consiglio Nazionale delle Ricerche (CNR-IGG) and of the Earth Sciences Department of the University of Florence (CNR/UF). The brittle layer (sand) thickness ranged between 6 and 20 mm, the underlying viscous layer, split in a competent and weak domain (both viscous mixtures), was always 10 mm thick. Asymmetric extension was applied by removing a 1.5 mm thick spacer at the side of the model at every time step, allowing the analogue materials to spread when enhanced gravity was applied during a centrifuge run.
Differential stretching of the viscous material creates flexure and faulting in the overlying brittle layer. Total extension amounted to 10.5 mm over 7 intervals for Series 1 models that aimed at understanding generic passive margin development in a generic orthogonal extension setting, whereas up to 16.5 mm of extension was applied for the additional Series 2 models aiming at reproducing the tectonic phases in Afar. In models involving sedimentation, sand was filled in at time steps 2, 4 and 6 (i.e. after 3, 6 and 9 mm of extension). Detailed descriptions of the experiments, monitoring techniques and tectonic interpretation of the model results are presented in Zwaan et al. (2020c) to which these data are supplementary.