Source: Journal of Geophysical Research: Solid Earth
The earth’s crust is constantly in motion. As the tectonic plates that make up the lithosphere move, separate, and crash into each other, the crust fractures and bends in response. Faults and folds occur at the fault folds, which are created by the ramp-low-cut systems, but the dynamics and timing of bending relative to seismic cycles are not well understood.
In search of answers, Mallick et al. developed a numerical model to simulate the folding of the brittle crust throughout the seismic cycle, which takes into account the mechanical relationship between fault slip and inelastic deformation outside the fault. The team derived the shear stress rate from the incremental strain using elastoplastic bending models and combined it with seismic sequence simulations and rate-state friction models of the evolution of the resistance of faults.
The authors found that the elastic response of the crust to fault slip can mask inelastic deformation of geodetic data during large earthquakes, but that it is possible to distinguish these signals in the post-earthquake period. They show that the rate of non-fault strain is closely related to fault slip, with the highest rates occurring during and immediately after earthquakes and logarithmically decreasing over time. In addition, they discovered that the type of rock present can influence this rate of relaxation.
To distinguish the geodesic signals of non-fault deformation from those of fault release, the authors recommend that future studies combine seismogeodetic observations with structural geological data on fault geometry. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2021JB022045, 2021)
—Kate Wheeling, science writer