Nowadays, technological advances in satellite imagery measurements as well as the development of dense geodetic and seismologic networks allow for a detailed analysis of surface deformation associated with active fault seismic cycle. However, the study of earthquake dynamics faces several limiting factors related to the difficulty to access the deep source of earthquake and to integrate the characteristic time scales of deformation processes that extend from seconds to thousands of years. To overcome part of these limitations and better constrain the role and couplings between kinematic and mechanical parameters, we have developed a new experimental approach allowing for the simulation of strike-slip fault earthquakes and analyze in detail hundreds of successive seismic cycle. Model rheology is made of multilayered visco-elasto-plastic analog materials to account for the mechanical behavior of the upper and lower crust and to allow simulating brittle/ductile coupling, postseismic deformation phase and far-field stress transfers. The kinematic evolution of the model surface is monitored using an optical system, based on subpixel spectral correlation of high-resolution digital images. First, results show that the model succeed in reproducing the deformation mechanisms and surface kinematics associated to the main phases of the seismic cycle indicating that model scaling is satisfactory. These results are comforted by using numerical algorithms to study the strain and stress distribution at the surface and at depth, along the fault plane. Our analog modeling approach appears, then, as an efficient complementary approach to investigate earthquake dynamics.

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Numerous dense geodetic observations over recent decades reveal that faults can experience a wide range of slip velocities, ranging from stable slow aseismic creep to fast dynamic instability of earthquakes. In this spectrum of fault slip, slow earthquakes exhibit an intermediate behavior between purely steady aseismic creep and regular earthquakes (

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Fault damage zones strongly influence fluid flow and seismogenic behavior of faults and are thought to scale linearly with fault displacement until reaching a threshold thickness. Using analog modeling with different frictional layer thicknesses, we investigate damage zone dynamic evolution during normal fault growth. We show that experimental damage zone growth with displacement is not linear but progressively tends toward a threshold thickness, being larger in the thicker models. This threshold thickness increases significantly at fault segment relay zones. As the thickness threshold is approached, the failure mode progressively transitions from dilational shear to isochoric shear. This process affects the whole layer thickness and develops as a consequence of fault segment linkage as inferred in nature when the fault matures. These findings suggest that fault damage zone widths are limited both by different scales of mechanical unit thickness and the evolution of failure modes, ultimately controlled in nature by lithology and deformation conditions.

We have developed a scaled analog model of a subduction zone simulating seismic cycle deformation phases. Its rheology is based on multilayered visco‐elasto‐plastic materials to account for the mechanical behavior of a continental lithospheric plate overriding a subducting oceanic plate. The seismogenic zone displays unstable slip behavior, extending at depth into a weak interface with stable slip properties. The model succeeds in reproducing interseismic phases interrupted by coseismic ruptures and followed by after‐slip. The experimental data catalog shows a broad variability of slip events from aseismic slow slips to fast dynamic lab quakes. Results also show the occurrence of both isolated and precursory slow‐slip events arising before the mainshocks. Given the absence of fluids in the model, the broad variability in slip event velocity can be attributed to fault roughness complexity. The model rheology induces also a key visco‐elastic coupling between the elastic overriding plate and the mantle wedge allowing, for the first time, to reproduce experimentally a realistic postseismic visco‐elastic relaxation phase. Preliminary results reveal that the tectonic loading rate modulates this visco‐elastic coupling. A low loading rate weakens it, which increase the amount of storable interseismic elastic deformation, and favors the occurrence of large megathrust events. A high loading rate strengthens it, which minimize the accumulation of interseismic elastic deformation, the slip‐event sizes, and promote aseismic creep. This new scaled‐analog subduction model is a complementary tool to investigate earthquake mechanics and improve the interpretation of geodetic and seismological records.

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Surface topography results from complex couplings and feedbacks between tectonics and surface processes. We combine analog and numerical modeling, sharing similar geometry and boundary conditions, to assess the topographic evolution of an alluvial fan crossed by an active thrust fault. This joint approach allows the calibration of critical parameters constraining the river deposition–incision laws, such as the settling velocity of suspended sediments, the bed-rock erodibility, or the slope exponent. Comparing analog and numerical models reveals a slope-dependent threshold process, where a critical slope of ca. 0.081 controls the temporal evolution of the drainage network. We only evidence minor topographic differences between stable and stick-slip fault behavior localized along the fault scarp. Although this topographic signature may increase with the slip rate and the return period of slip events, it remains slight compared to the cumulated displacement along the fault scarp. Our results demonstrate that the study of morphology cannot be used alone to study the slip mode of active faults but can be a valuable tool complementing stratigraphic and geodetic observations. In contrast, we underline the significant signature of the distance between the fault and the sediment source, which controls the degree of channels incision and the density of the drainage network.