Effect of Fault Roughness on Aftershock Distribution: Plastic Off‐Fault Material Properties. Issue 7 (22nd July 2019)

• Record Type: Journal Article
• Authors: Aslam, Khurram S.; Daub, Eric G.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 7(2019)
• Page Start: 6989
• Page End: 7012
• Publication Date: 2019-07-22
• Subjects: dynamic rupture simulation -- spatial aftershocks analysis -- Coulomb stress calculation -- off‐fault stress heterogeneity -- fault roughness -- damage zone and aftershocks; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2019JB017392
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: We perform spontaneous earthquake rupture simulations on rough strike‐slip faults with off‐fault plastic material properties. We examine the off‐fault stress change and coseismic damage pattern resulting from dynamic fault slip. We use the stress output from each simulation to calculate the Coulomb failure function (CFF). We calculate the CFF values on the extensional and compressional side of the fault using parallel receiver fault orientations. We also calculate the CFF values on the extensional side of the fault using variable receiver fault orientations determined using the angle at which plastic shear strain is maximum. We calculate the probability density function for the CFF values across the fault as a function of distance. We observe a similar overall trend of the CFF values with distance for the extensional and compressional sides—our simulations show a broad range of values in the near‐fault region, while a narrow range of values occurs further from the fault. In the near‐fault region, we observe many more positive CFF change zones using variable receiver fault orientations than using parallel orientations. We calculate the areas and amplitudes of these positive CFF zones as a function of distance away from the fault. Our comparison of CFF amplitudes as a function of rupture area suggests that the spatial aftershock distribution surrounding a fault is controlled by both stress heterogeneity and the coseismic damage zone complexity. The calculations of rupture areas using our model are consistent with ruptured areas of observed aftershocks in California. Key Points: We perform spontaneous earthquake rupture simulations on rough strike‐slip faults with off‐fault plastic material properties We calculate the Coulomb stress change in the off‐fault material using spatially variable receiver fault orientations We investigate the relationship of aftershock seismicity with the damage zone and multiple‐receiver fault orientations