Browsing by Author "Herrera, Marco T."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A proxy implementation of thermal pressurization for earthquake cycle modelling on rate-and-state faults
    (2024) Herrera, Marco T.; Ampuero, Jean P.; Crempien, Jorge G. F.
    The reduction of effective normal stress during earthquake slip due to thermal pressurization of fault zone pore fluids is a significant fault weakening mechanism. Explicit incorporation of this process into frictional fault models involves solving the diffusion equations for fluid pressure and temperature outside the fault at each time step, which significantly increases the computational complexity. Here, we propose a proxy for thermal pressurization implemented through a modification of the rate-and-state friction law. This approach is designed to emulate the fault weakening and the relationship between breakdown energy and slip resulting from thermal pressurization and is appropriate for fully dynamic simulations of multiple earthquake cycles. It preserves the computational efficiency of conventional rate-and-state friction models, which in turn can enable systematic studies to advance our understanding of the effects of fault weakening on earthquake mechanics. In 2.5-D simulations of pulse-like ruptures on faults with finite seismogenic width, based on our thermal pressurization proxy, we find that the spatial distribution of slip velocity near the rupture front is consistent with the conventional square-root singularity, despite continued slip-weakening within the pulse, once the rupture has propagated a distance larger than the rupture width. An unconventional singularity appears only at shorter rupture distances. We further derive and verify numerically a theoretical estimate of the breakdown energy dissipated by our implementation of thermal pressurization. These results support the use of fracture mechanics theory to understand the propagation and arrest of very large earthquakes.
  • No Thumbnail Available
    Item
    Complex Crustal Deformation Controlled by the 3D Geometry of the Chile Subduction Zone
    (2023) Herrera, Marco T.; Crempien, Jorge G. F.; Cembrano, Jose
    The Chilean subduction zone hosts Mw > 8 earthquakes, which could trigger earthquakes on crustal faults located along the plate margin. Using synthetic earthquakes from a quasidynamic boundary element method model, we obtain traction fields and perform a slip tendency analysis to obtain synthetic faults, which we compare with existing potentially seismogenic crustal faults. With our results, we find geometric patterns of the highest slip tendency planes with deformations induced by synthetic subduction events, such that north of the rupture area of each event, correlate with normal N20(degrees)W-50(degrees)W/N60(degrees)SW fault planes, and to the south, correlate with normal N30(degrees)E-80(degrees)E/N60(degrees)NW faults planes. These observations agree with observed fault traces in central and northern Chile, and past observations of crustal fault reactivation.
  • Thumbnail Image
    Item
    Seismic cycle controlled by subduction geometry: novel 3-D quasi-dynamic model of Central Chile megathrust
    (2024) Herrera, Marco T.; Crempien, Jorge G. F.; Cembrano, Jose; Moreno, Marcos
    Subduction earthquakes show complex spatial and temporal rupture patterns, exhibiting events of varied sizes, which rupture distinct or overlapping fault segments. Elucidating first-order controlling conditions of rupture segmentation and return periods of large earthquakes is therefore critical for seismic and tsunami hazard estimations. The Chilean subduction zone frequently hosts several M-w > 8 earthquakes, with heterogeneous recurrence rates and locations. Here, we implement 3-D quasi-dynamic rate and state frictional models to investigate the role of plate interface geometry on the distribution of interseismic coupling and coseismic ruptures in Central Chile. First, we develop synthetic-parametric models that show how dip and strike variations may increase the probabilities to produce partial seismic barriers, which tend to avoid the production of large earthquake ruptures and modulate rupture lengths. Then, we simulate the subduction seismic cycle processes on Central Chile (25(degrees)S-38(degrees)S), imposing depth-dependent frictional properties on a realistic non-planar 3-D subduction interface geometry. Similar to results obtained for synthetic-parametric models, after 5000 yr of simulation, regions with abrupt dip or strike changes increase the probabilities of stopping coseismic propagation of simulated M-w 8.0-9.0 earthquakes. Our simulated earthquake sequences on the Central Chile subduction zone delimit rupture areas that match geometrical interface features and historical earthquakes, results that point to the crucial role of fault interface geometry on seismic cycle segmentation along strike.