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The Congo basin (CB) occupies a large part of the Congo Craton (1.2 million km2) covering approximately 10% of the continent. It contains up to 9 km of sedimentary rocks from Mesozoic until Quaternary age. The formtion of the CB started with a rifting phase during the amalgamation of the Rodinia supercontinent at ~ 1.2 Gyr and the main episodes of subsidence occurred during the following post-rift phases in the Neoproterozoic and Paleozoic, separated by late Pan-African compressional inversion [1]. After a new compressional inversion at the end of the Permian, sedimentation resumed during the Mesozoic; since Cretaceous, the CB has been subjected to an intraplate compressional settng due to ridge-push forces related to the spreading of the South Atlantic Ocean [1]. In this study we first interpreted the seismic reflection profiles and well logs data located inside the central area of the CB, to reconstruct the stratigraphy/tectonic evolution of the basin. Afterwards, we compared geological and geographycal information to estimate the velocity, density, thickness of the sedimentary layers and the depth of the lithostratigraphic units. The results have been used as input parameters for a 3D numerical simulations, testing the main mechanisms of formation and evolution of the CB. To study this, we used the 3D thermomechanical code I3ELVIS [2] to simulate the initial rift phases. For the first experiments, we assumed that the Congo craton is made of four blocs of Archean age. We applied extensional stresses in the N-S and E-W directions (orthogonal stresses) [1] to test the hypothesis of the formation of a multi extensional rift in a cratonic area. The results of these first numerical experiments show that the deformation is localized in the central part of the CB. [1] De Wit, M.J., Stankiewicz, J., Reeves, C.V., (2008), Restoring Pan-African-Brasiliano connections: more Gondwana control, less Trans Atlantic corruption, 294, 10.1144/SP294.20, Geological Society, London, Special publications. [2] Gerya, T., Introduction to numerical geodynamic modelling, Cambridge University Press. T. Gerya 2009.

The imprint of the interaction between shallow and deep Earth processes controlling the evolution of the cratoinc lithosphere is left in their sedimentary record. We focused our study on the Congo Basin (CB) which occupies a large part of the Congo Craton and contains up to 9 km of sedimentary rocks from Mesoproterozoic until Quaternary age. The formation of the CB started with a rifting phase during the amalgamation of the Rodinia supercontinent (~1.2 Gyr) and evolved through the following post-rift phases and successive phases of compression. We reconstructed the stratigraphy and tectonic evolution of the Congo basin by interpreting the seismic reflection profiles and well logs data located inside the central area of the CB. The results obtained are successively validated by analysing the relationship between topography and Bouguer anomalies. In this way, we could localize the mafic intrusions at the base and through the sedimentary sequence and thus dentify the rift shape. Afterwards, we performed 3D numerical simulations using I3ELVIS code to simulate the initial rift phases. We considered the Congo craton as composed of four cratonic blocks and applied extensional stress in two orthogonal directions to test the hypothesis of the formation of a multi extensional rift in a cratonic area. We repeated the numerical simulations changing the geometries and thicknesses of the cratonic blocks, as well as their physical parameters (e.g., temperature and rheology), in order to get the best agreement with the results obtained from the previous analysis of the geological and geophysical data.

Natural fault networks are geometrically complex systems that evolve through time. The evolution of faults and their off-fault damage patterns are influenced by both dynamic earthquake ruptures and aseismic deformation in the interseismic period. To better understand each of their contributions to faulting we simulate both earthquake rupture dynamics and long-term deformation in a visco-elasto-plastic crust subjected to rate- and state-dependent friction. The continuum mechanics-based numerical model presented here includes three new features. First, a 2.5-D approximation is created to incorporate the effects of a viscoelastic lower crustal substrate below a finite depth. Second, we introduce a dynamically adaptive (slip-velocity-dependent) measure of fault width to ensure grid size convergence of fault angles for evolving faults. Third, fault localization is facilitated by plastic strain weakening of bulk rate and state friction parameters as inspired by laboratory experiments. This allows us to simulate sequences of episodic fault growth due to earthquakes and aseismic creep for the first time. Localized fault growth is simulated for four bulk rheologies ranging from persistent velocity weakening to velocity strengthening. Interestingly, in each of these bulk rheologies, faults predominantly localize and grow due to aseismic deformation. Yet, cyclic fault growth at more realistic growth rates is obtained for a bulk rheology that transitions from velocity-strengthening friction to velocity-weakening friction. Fault growth occurs under Riedel and conjugate angles and transitions towards wing cracks. Off-fault deformation, both distributed and localized, is typically formed during dynamic earthquake ruptures. Simulated off-fault deformation structures range from fan-shaped distributed deformation to localized splay faults. We observe that the fault-normal width of the outer damage zone saturates with increasing fault length due to the finite depth of the seismogenic zone. We also observe that dynamically and statically evolving stress fields from neighboring fault strands affect primary and secondary fault growth and thus that normal stress variations affect earthquake sequences. Finally, we find that the amount of off-fault deformation distinctly depends on the degree of optimality of a fault with respect to the prevailing but dynamically changing stress field. Typically, we simulate off-fault deformation on faults parallel to the loading direction. This produces a 6.5-fold higher off-fault energy dissipation than on an optimally oriented fault, which in turn has a 1.5-fold larger stress drop. The misalignment of the fault with respect to the static stress field thus facilitates off-fault deformation. These results imply that fault geometries bend, individual fault strands interact, and optimal orientations and off-fault deformation vary through space and time. With our work we establish the basis for simulations and analyses of complex evolving fault networks subject to both long-term and short-term dynamics.

This data publication is supplementary material to the paper " Subduction initiation by plume-plateau interaction: Insights from numerical models" (Baes et al., 2020). In this study, using 3-d numerical models, we explore the effect of relative distance of plume head and plateau edge, age of the lithosphere and strength of the lower crust on plume-induced subduction initiation. We use I3ELVIS code which solves the momentum, continuity and energy equations based on a staggered finite difference scheme combined with a marker-in-cell technique (Gerya, 2010; Gerya et al., 2015; Baes et al., 2016). Our numerical results show four different responses (shown in Figures 2-5 in the paper of Baes et al, 2020) that are: (a) oceanic trench formation, (b) circular plateau-oceanic trench formation, (c) plateau trench formation and (d) no trench formation. The results of models in which plume head is far away from the plateau edge are compatible with the outcomes of models with uniform lithospheres. The current data set contains the figures of five models representing five different deformation regimes (shown in Fig. 7 in the paper), which result from interaction of a plume with a homogenous lithosphere. Note that in all figures the upper panels show the logarithm of viscosity within the lithosphere. The middle and lower panels illustrate compositional field of a 2d cross-section cutting through center of model and surface topography, respectively. The color bars of temperature field and surface topography are shown at the top of the figure and colour code of compositional field is at bottom of the figure.

The data are the numerical modeling results to investigate plume-induced subduction initation on which the figures of the paper "Plume-induced subduction initiation: single- or multi-slab subduction?" by Baes, Sobolev, Gerya and Brune are based. Detailed description on how they are obtained is given in that article (Baes et al., 2020). The naming of the files is based on the number of figures in the paper. Each zipped file contains input files (init.t3c and mode.t3c) and output files (*.vtr).

Orientations of natural fault systems are subject to large variations. They often contradict classical Andersonian faulting theory as they are misoriented relative to the prevailing regional stress field. This is ascribed to local effects of structural or stress heterogeneities and reorientations of structures or stresses on the long-term. To better understand the relation between fault orientation and regional stresses, we simulate spontaneous fault growth and its effect on the stress field. Our approach incorporates earthquake rupture dynamics, visco-elasto-plastic brittle deformation and a rate-and state- dependent friction formulation in a continuum mechanics framework. We investigate how strike slip faults orient according to local and far-field stresses during their growth. We identify two modes of fault growth, seismic and aseismic, distinguished by different fault angles and slip velocities. Seismic fault growth causes a significant elevation of dynamic stresses and friction values ahead of the propagating fault tip. These elevated quantities result in a greater strike angle relative to the maximum principal regional stress than that of a fault segment formed aseismically. When compared to the near-tip time-dependent stress field the fault orientations produced by both growth modes follow Anderson’s classical faulting theory. We demonstrate how the two types of fault growth may be distinguished in natural faults by comparing their angles relative to the original regional max- imum principal stress. A stress field analysis of the Landers-Mojave fault suggests that an angle greater than approximately 25° between two faults indicates seismic fault growth.

There is increasing evidence that the Himalayan seismicity can be bimodal: blind earthquakes (up to Mw ~ 7.8) tend to cluster in the downdip part of the seismogenic zone, whereas infrequent great earthquakes (Mw 8+) propagate up to the Himalayan frontal thrust. To explore the causes of this bimodal seismicity, we developed a two-dimensional, seismic cycle model of the Nepal Himalaya. Our visco-elasto-plastic simulations reproduce important features of the earthquake cycle, including interseismic strain and a bimodal seismicity pattern. Bimodal seismicity emerges as a result of relatively higher friction and a non-planar geometry of the Main Himalayan Thrust fault. This introduces a region of large strength excess that can only be activated once enough stress is transferred upwards by blind earthquakes. This supports the view that most segments of the Himalaya might produce complete ruptures significantly larger than the 2015 Mw 7.8 Gorkha earthquake, which should be accounted for in future seismic hazard assessments., Nature Communications, 10, ISSN:2041-1723