Scientists' laboratory tests have revealed that the degree of roughness of the rocks rubbing against one another in a fault zone may be a significant factor in the generation of aftershocks following an earthquake event. Goebel et al. just published a paper in Geophysical Research Letters outlining the findings.

The researchers pressed granite cylinders with fractures of various roughness to represent sliding motions along a fault. They used acoustic emission wave measurements to take high resolution measurements of the ensuing seismic disturbances. The main slides, foreshocks, and aftershocks in the models matched the spacing and timing of the actual Southern California earthquakes.

Greater fracture roughness resulted in less movement along the fracture during the main slip event but more aftershocks, according to the researchers, whereas smoother fractures resulted in more slip but fewer aftershocks. These results indicate that the production of aftershocks following a major earthquake event may be significantly influenced by fault surface roughness in nature.

The findings may aid in quantifying seismic threats and advances our knowledge of earthquake dynamics. Scientists may be better able to forecast the likelihood of aftershocks and their possible damage on infrastructure and communities by untangling the elements that contribute to shaking sequences.

Credits belong to science writer Sarah Stanley. Geophysical Research Letters, 2023. Available at: https://doi.org/10.1029/2022GL101241, 2023.