This repository provides the code and data to run the Seismo-Thermo-Mechanical model with a sediment thickness Tsed of 4 km on a cluster using executables.
We use two‐dimensional numerical experiments to investigate the long‐term dynamics of an oceanic slab. Two problems are addressed: one concerning the influence of rheology on slab dynamics, notably the role of elasticity, and the second dealing with the feedback of slab‐mantle interaction to be resolved in part 2. The strategy of our approach is to formulate the simplest setup that allows us to separate the effects of slab rheology (part 1) from the effects of mantle flux (part 2). Therefore, in this paper, we apply forces to the slab using simple analytical functions related to buoyancy and viscous forces in order to isolate the role of rheology on slab dynamics. We analyze parameters for simplified elastic, viscous, and nonlinear viscoelastoplastic single‐layer models of slabs and compare them with a stratified thermomechanical viscoelastoplastic slab embedded in a thermal solution. The near‐surface behavior of slabs is summarized by assessing the amplitude and wavelength of forebulge uplift for each rheology. In the complete thermomechanical solutions, vastly contrasting styles of slab dynamics and force balance are observed at top and bottom bends. However, we find that slab subduction can be modeled using simplified rheologies characterized by a narrow range of selected benchmark parameters. The best fit linear viscosity ranges between 5 × 10 22 Pa s and 5 × 10 23 Pa s. The closeness of the numerical solution to nature can be characterized by a Deborah number >0.5, indicating that elasticity is an important ingredient in subduction.
Abstract Subducting seamounts are recognized as one of the key features influencing megathrust earthquakes. However, whether they trigger or arrest ruptures remains debated. Here, we use analog models to study the influence of a single seamount on megathrust earthquakes, separating the effect of topography from that of friction. Four different model configurations have been developed (i.e., flat interface, high and low friction seamount, low friction patch). In our models, the seamount reduces recurrence time, interseismic coupling, and fault strength, suggesting that it acts as a barrier: 80% of the ruptures concentrate in flat regions that surround the seamount and only smaller magnitude earthquakes nucleate above it. The low‐friction zone, which mimics the fluid accumulation or the establishment of fracture systems in natural cases, seems to be the most efficient in arresting rupture propagation in our experimental setting.
This work is part of the projects ALPIMED (PIE-CSIC-201530E082) and MITE (CGL2014-59516-P). We
also thank to the project AECT-2017-3-0008 of the Barcelona Supercomputing center (BSC-CNS).
<p>The use of experimental tectonics (also known as analogue-, laboratory, or physical modelling) to study tectonic processes is not a novelty in Earth Science. Following Sir James Hall&#8217;s pioneer work (1815), many modellers squeezed, stretched, pushed and pulled a wide range of materials &#8211; e.g., sand, clay, oil, painters&#8217; putties, gelatins, wax, paraffin, syrups, polymers &#8211; to unravel a wide range of tectonic processes to determine parameters controlling their geometry, kinematics and dynamics. However, only recently experimental analogue modelling has definitively transformed from a qualitative to a quantitative technique, thanks to appropriate scaling relationships, the improvement in the knowledge of the rheology of both natural and analogue materials and the use of high-resolution monitoring techniques to quantify morphology, kinematics, stress, strain and temperature.</p><p>Here, I specifically review the experimental work performed to study one of the most intriguing aspects of plate tectonics: the subduction process. Subduction provides the dominant engine for plate tectonics and mantle dynamics. Moreover, it has also societal importance playing a key role on hazard at short (i.e., earthquakes and mega-earthquakes, tsunami, effusive and&#160;explosive volcanic activities with impact on aviation safety) and long time scales (i.e., local and global climate change). Over the last decades, a noteworthy advance in the quality and density of global geological, geophysical and experimental data has allowed us to provide systematic quantitative analyses of global subduction zones and to speculate on their behaviour. These constraints have been integrated into a mechanical framework through modelling.</p><p>I will bring you to a journey through the past, the present and the future of analogue modelling and related efforts, results and perspectives for the study of the subduction process. It will be shown how analogue models, with their inherent 3D character and behaviour driven by simple and natural physical laws, contribute to successfully unravelling the subduction process, inspiring new ideas. Challenging ongoing perspectives of analogue models imply the possibility to compare time and space scales, allowing to merge, within the same model, both short- and long-term and shallow and deep processes.</p>
Volcanological and structural field data are used to define the tectonic control on the N–S volcanic arc of NE Honshu (Japan) since late Miocene. During late Miocene‐Pliocene, bimodal products were mainly erupted from along‐arc and NE–SW‐aligned and elongated calderas. The deformation pattern mostly consisted of N–S dextral faults and subordinate NE–SW extensional structures produced by NE–SW compression. This pattern, because of the indentation of the Kuril sliver, is similar to that of oblique convergence settings. Magma rose and extruded along NE–SW areas of localized extension created by the dextral faults. These extensional areas were uncoupled with regard to those, ∼E–W trending, inferred to have focused the rise of melts from the subducting slab in the mantle. During Quaternary, a larger amount of andesite was mainly erupted from along‐arc and ∼E–W‐aligned and elongated stratovolcanoes. The deformation pattern mostly consisted of N–S thrust faults and subordinate ∼E–W extensional structures, produced by ∼E–W compression, resulting from orthogonal convergence due to the variation in the absolute motion of the Pacific Plate. The ∼E–W extensional structures are the shallowest expression of ∼E–W‐trending hot mantle fingers, suggesting mantle‐crust coupling for the rise of magma. Such a coupling ensures (1) higher extrusion and (2) mixing between a deeper mafic and a shallower felsic magma, generating the andesites. The significantly larger volumes (Ma −1 200 km −1 of length of the arc) of magma erupted during Quaternary show that pure convergence conditions do not necessarily hinder the rise and extrusion of magma.
Abstract. Continental collision is an intrinsic feature of plate tectonics. The closure of an oceanic basin leads to the onset of subduction of buoyant continental material, which slows down and eventually stops the subduction process. We perform a parametric study of the geometrical and rheological influence on subduction dynamics during the subduction of continental lithosphere. In 2-D numerical models of a free subduction system with temperature and stress-dependent rheology, the trench and the overriding plate move self-consistently as a function of the dynamics of the system (i.e. no external forces are imposed). This setup enables to study how continental subduction influences the trench migration. We found that in all models the trench starts to advance once the continent enters the subduction zone and continues to migrate until few million years after the ultimate slab detachment. Our results support the idea that the trench advancing is favoured and, in part provided by, the intrinsic force balance of continental collision. We suggest that the trench advance is first induced by the locking of the subduction zone and the subsequent steepening of the slab, and next by the sinking of the deepest oceanic part of the slab, during stretching and break-off of the slab. The amount of trench advancing ranges from 40 to 220 km and depends on the dip angle of the slab before the onset of collision.
