Einat Aharonov

• Sarma, Pritom; Aharonov, Einat; Toussaint, Renaud & Parez, Stanislav (2025). Fault Gouge Failure Induced by Fluid Injection: Hysteresis, Delay and Shear‐Strengthening. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 130(6). doi: 10.1029/2024jb030768. Fulltekst i vitenarkiv Vis sammendrag

  Natural faults often contain a fluid‐saturated, granular fault‐gouge layer, whose failure and sliding processes play a central role in earthquake dynamics. Using a two‐dimensional discrete element model coupled with fluid dynamics, we simulate a fluid‐saturated granular layer, where fluid pressure is incrementally raised. At a critical fluid pressure level, the layer fails and begins to accelerate. When we gradually reduce fluid pressure, a distinct behavior emerges: slip‐rate decreases linearly until the layer halts at a fluid pressure level below that required to initiate failure. During this pressure cycle the system exhibits (a) velocity‐strengthening friction and (b) frictional hysteresis. These behaviors, well established in dry granular media, are shown to extend here to shear of dense fluid‐saturated granular layers. Additionally, we observe a delay between fluid pressure increase and failure, associated with pre‐failure dilative strain and “dilational‐hardening.” During this delay period, small, arrested slip events dilate the layer in preparation for full‐scale failure. Our findings may explain (a) fault motion that continues even after fluid pressure returns to pre‐injection levels, and (b) delayed failure in fluid‐injection experiments, and (c) pre‐failure arrested slip events observed prior to earthquakes.

• Barras, Fabian; Aharonov, Einat & Renard, Francois (2025). A Minimal Model Illuminates the Physics of Pulse-Like Seismic Rupture and Oscillatory Slip Rates in Damaged Faults. Geophysical Research Letters. ISSN 0094-8276. 52(4). doi: 10.1029/2024GL111189. Fulltekst i vitenarkiv Vis sammendrag

  Fault zones are often surrounded by a damage zone that exhibits lower seismic velocities than the wall rock, influencing earthquake propagation and arrest. We present a one-dimensional minimal model of frictional rupture that approximates the elastodynamics of a fault embedded within a damage zone. This model predicts two families of steady-state rupture solutions: an overdamped regime, describing a crack-like rupture, and an underdamped regime with oscillating slip-rate in the wake of the rupture, which promotes pulse-like dynamics. The minimal model contains two free parameters: the pre-stress on the fault, and the seismic velocity reduction in the damage zone. We present how the one-dimensional prediction is consistent with previously published two-dimensional simulations and discuss the applicability of our results to natural observations, identifying the preferred rupture style as function of structure of the fault zone, and the geological consequences of oscillatory slip in the wake of pulse-like ruptures.

• Moneron, Jimmy; Gvirtzman, Zohar; Karcz, Zvi; Shitrit, Omri; Sagy, Yael & Aharonov, Einat (2025). Exploring the relationship between sedimentary transport systems and basin dynamics: A case study from the Levant Basin (Eastern Mediterranean Sea) before, during, and after the Messinian. Geological Society of America Bulletin. ISSN 0016-7606. 137(3-4), s. 1423–1436. doi: 10.1130/B37589.1. Fulltekst i vitenarkiv Vis sammendrag

  Submarine channels serve as routes transporting sediments across hundreds of kilometers from continental margins to the deepest parts of a basin’s seafloor. Consequently, owing to the influential role of gravity in determining the flow direction, these channels typically follow the steepest sloping paths, making paleo-drainage systems essential in reconstructing basin dynamics over geological periods. This research aims to document the interrelationships between tectonic tilting, rapid deposition of salt, and delta sediment propagation on basin morphology and consequently on sedimentary transport orientation. Here, we examine how the interplay between these geological processes influenced the orientation of submarine channels in the Levant Basin, our case study, over ~10 m.y. During the late Miocene, sediments originating from the Levant continental margin were transported to the deep parts of the Eastern Mediterranean Sea (i.e., the Herodotus Basin) via a tectonic valley active until the Messinian Salinity Crisis. Later, exceptionally fast burial by salt and subsequent truncation of this evaporitic layer produced a nearly horizontal seafloor that redirected the regional drainage toward the basin’s center, with no connection to the adjacent and much deeper Herodotus Basin. This drainage configuration did not last long since tilting of the basin northward toward the Cyprus subduction zone and northward propagation of the Nile delta have rapidly reshaped basin morphology, resulting in a rotation of major sedimentary routes in the area. From a broad perspective, this research not only exemplifies how rapid salt burial can reset a basin’s drainage system but also has implications for geodynamic and geomorphic processes in evaporite-bearing sedimentary basins within tectonically active areas.

• Ben-Zeev, Shahar; Goren, Liran; Toussaint, Renaud & Aharonov, Einat (2023). Drainage explains soil liquefaction beyond the earthquake near-field. Nature Communications. 14(1). doi: 10.1038/s41467-023-41405-4. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Earthquake-induced soil-liquefaction is a devastating phenomenon associated with loss of soil rigidity due to seismic shaking, resulting in catastrophic liquid-like soil deformation. Traditionally, liquefaction is viewed as an effectively undrained process. However, since undrained liquefaction only initiates under high energy density, most earthquake liquefaction events remain unexplained, since they initiate far from the earthquake epicenter, under low energy density. Here we show that liquefaction can occur under drained conditions at remarkably low seismic-energy density, offering a general explanation for earthquake far-field liquefaction. Drained conditions promote interstitial fluid flow across the soil during earthquakes, leading to excess pore pressure gradients and loss of soil strength. Drained liquefaction is triggered rapidly and controlled by a propagating compaction front, whose velocity depends on the seismic-energy injection rate. Our findings highlight the importance of considering soil liquefaction under a spectrum of drainage conditions, with critical implications for liquefaction potential assessments and hazards.

• Barras, Fabian; Thøgersen, Kjetil; Aharonov, Einat & Renard, Francois (2023). How Do Earthquakes Stop? Insights From a Minimal Model of Frictional Rupture. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 128(8). doi: 10.1029/2022JB026070. Fulltekst i vitenarkiv Vis sammendrag

  The question “what arrests an earthquake rupture?” sits at the heart of any potential prediction of earthquake magnitude. Here, we use a one-dimensional, thin-elastic-strip, minimal model, to illuminate the basic physical parameters that may control the arrest of large ruptures. The generic formulation of the model allows for wrapping various earthquake arrest scenarios into the variations of two dimensionless variables Tk (initial dimensionless stress parameter on the fault) and Gc (dimensionless fracture energy), valid for both in-plane and antiplane shear loading. Our continuum model is equivalent to the standard Burridge-Knopoff model, with an added characteristic length scale, H, that corresponds to either the thickness of the damage zone for strike-slip faults or to the thickness of the downward moving plate for subduction settings. We simulate the propagation and arrest of frictional ruptures and derive closed-form expressions to predict rupture arrest under different conditions. Our generic model illuminates the different energy budget that mediates crack- and pulse-like rupture propagation and arrest. It provides additional predictions such as generic stable pulse-like rupture solutions, stress drop independence of the rupture size, the existence of back-propagating fronts, and predicts that asymmetric slip profiles arise under certain pre-stress conditions. These diverse features occur also in natural earthquakes, and the fact that they can all be predicted by a single minimal framework is encouraging and pave the way for future developments of this model.

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• Barras, Fabian; Aspaas, Andreas Grøvan; Aharonov, Einat & Renard, Francois (2026). Unveiling the role of seepage forces in the acceleration of frictional creep in fluid-saturated shear zone. doi: 10.5194/egusphere-egu26-17167. Fulltekst i vitenarkiv Vis sammendrag

  How fluid impact frictional slip is a central question in various geological settings, from tectonic faults to friction at the base of glaciers. In this work, we study the impact of fluid infiltration on the creep dynamics of the shear zone located at the base of a densely monitored landslide in Western Norway. In Åknes, approximately 50 million cubic meter of rock mass continuously creeps over a shear zone made of rock fragments, with seasonal accelerations that strongly correlate with rainfall. In this natural laboratory for fluid-induced frictional creep, unprecedented monitoring equipment reveals low fluid pressure across the shear zone, thereby challenging the conventional theory of fluid-driven instability in landslides. Here, we show that a generic micromechanical model can disentangle the effects of fluid flow from those of fluid pressure, and demonstrate that seepage forces applied by channelized flow along the shear zone are the main driver of creep accelerations. We conclude by discussing the significance of seepage forces, the implications for hazard mitigation and the broader applicability of our model to various geological contexts governed by friction across saturated shear zones.

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