Earthquake catalog simulations with slip-dependent fracture energy

Earthquakes are the manifestation of rapid and catastrophic strain release in Earth’s crust. At present, the occurrence and statistical distribution of earthquakes is not completely clear. One of the main debates concerns the relative importance of energy dissipation through friction and fracture, as the predominant dissipation mechanism controls the dynamics of rupture propagation and how it should be represented in numerical models. In this thesis, I develop a 3D model of seismic event propagation based on fracture energy, which I assume to increase with slip according to empirical scaling laws estimated from seismological data. I consider a transform fault zone composed of patches of different sizes, whose orientations are perturbed, and circular ruptures that can propagate in different directions. Finally, I apply the model to the Húsavík-Flatey Fault, a fault zone characterized by abundant seismic swarms in its western portion and relatively few events in its eastern portion, possibly due to stress interactions with the Krafla Rifting Episode, a sequence of magmatic intrusions that occurred between 1975–1984. Despite the simplifications introduced, the model qualitatively captures several features of the observed behaviour, including the presence of a stress shadow that attenuates over time, depending on the magnitude of the perturbation, in the compressional zone of the fault, as well as increased seismicity in the extensional zone. The model also suggests that stress interactions may modify the fault’s seismic coupling degree, promoting aseismic slip in extensional regions, in agreement with previous studies in the literature. Future studies on the implications of assuming empirical scaling relations for fracture energy, as well as on the effects of stress variations induced by external processes, may benefit from this preliminary analysis.