“Opening on nonplanar faults and shear ruptures in heterogeneous, elastic media – Two new simulation methods for two long-avoided problems”

Crustal faults are naturally rough, or nonplanar, on length scales ranging from sub-millimeters to kilometers. Therefore, shear slip can induce significant perturbations in fault-normal stress. As a result, faults may open, where effective normal stress is low and where bulk cohesion is high. These conditions likely exist for faults under high pore fluid pressures. However, opening is typically explicitly prevented in existing earthquake sequence simulations.
Crustal faults naturally crosscut heterogeneous elastic media, due to inherited geological structures or evolving damage/recovery from past earthquakes. Heterogeneous elastic moduli not only modify nucleation length scales but also stress interactions on the fault. However, heterogeneous elastic properties near the fault are mostly ignored in existing earthquake sequence simulations.
I will present on two recently developed methods for efficiently modeling such geometric and material heterogeneities: a Spectral Boundary Element (SBEM) method to model mild nonplanarity of the fault, allowing the fault to open, and a Fourier Neural Operator (FNO) augmented boundary element method to model (evolving) off-fault elastic heterogeneities.
Simulations, inspired by faulting scenarios in crack-seal textures in exhumed subduction zones, self-similar rough faults, and realistic heterogeneous media, will be presented.

Earth Science Seminar —

Lecture portion of the EAPS graduate-level class 12.571, covering current research in geophysics, geology, geochemistry, and geobiology. All members of the MIT community are welcome to join for presentations by guest speakers, held approximately every two weeks during the term.

Contact: earth-science-seminar-info@mit.edu