Thèse

Vendredi 4 Septembre 2026 à 14h00.

From criticality to earthquake-like dynamics: towards understanding scale-invariant behavior beyond the τ = 3/2 limit

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Directeur de thèse / thesis director :
Osvanny Ramos, François Detcheverry

Membres du jury / jury members :
Daniel BONAMY, Directeur de recherche CEA Saclay, Rapporteur
Alberto ROSSO, Directeur de recherche CNRS Université Paris-Saclay, Rapporteur
Catherine BARENTIN, Professeur des Universités Lyon 1 Université, Examinatrice
Kirsten MARTENS, Chargée de Recherche CNRS Université Grenoble Alpes, Examinatrice
François PÉTRÉLIS, Directeur de Recherche CNRS ENS Paris, Examinateur
Valérie VIDAL, Directrice de Recherche CNRS ENS de Lyon, Examinatrice

Résumé / Abstract :
Power-law distributions are a common signature of critical phenomena and are widely observed in natural systems displaying scale-free behavior. The concept of self-organized criticality proposes that slowly driven dissipative systems can spontaneously evolve towardsuch critical states without external fine-tuning. While numerous theoretical approaches converge to an upper limit of 3/2 for the avalanche size exponent, many natural phenomena, such as earthquakes, exhibit exponents exceeding this value.

In this thesis, we focus on the original Olami-Feder-Christensen model, introduced in 1992 by Olami et al., as a simplified numerical model of earthquake dynamics. A distinctive feature of the OFC model is that, within a single framework, the avalanche exponent varies continuously with the level of dissipation, including regimes where τ > 3/2, making the model a natural framework for investigating the origin of the broad range of exponents observed in experiments.

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