2020/07/19 by F. M. Aben, Aben, Franciscus M., Nicolas Brantut +3 · 1 citation
Earth and Planetary Sciences · Engineering · #FOS: Physical sciences #Geophysics (physics.geo-ph) #Rock Mechanics and Modeling #Seismic Imaging and Inversion Techniques #Seismic Waves and Analysis #earthquake and tectonic studies
paper · pdf · doi:10.48550/arxiv.2007.09687
openalex publication_date 2020/07/19 · openalex created_date 2022/07/26 · openalex updated_date 2026/07/28
Elastic strain energy released during shear failure in rock is partially\nspent as fracture energy \Γ to propagate the rupture further. \Γ is\ndissipated within the rupture tip process zone, and includes energy dissipated\nas off-fault damage, \Γ_\off. Quantifying off-fault damage formed\nduring rupture is crucial to understand its effect on rupture dynamics and\nslip-weakening processes behind the rupture tip, and its contribution to\nseismic radiation. Here, we quantify \Γ_\off and associated\nchange in off-fault mechanical properties during and after quasi-static and\ndynamic rupture. We do so by performing dynamic and quasi-static shear failure\nexperiments on intact Lanh 'elin granite under triaxial conditions. We quantify\nthe change in elastic moduli around the fault from time-resolved 3D P-wave\nvelocity tomography obtained during and after failure. We measure the off-fault\nmicrofracture damage after failure. From the tomography, we observe a localised\nmaximum 25 % drop in P-wave velocity around the shear failure interface for\nboth quasi-static and dynamic failure. Microfracture density data reveals a\ndamage zone width of around 10 mm after quasi-static failure, and 20 mm after\ndynamic failure. Microfracture densities obtained from P-wave velocity\ntomography models using an effective medium approach are in good agreement with\nthe measured off-fault microfracture damage. \Γ_\off obtained\nfrom off-fault microfracture measurements is around 3 kJm2 for\nquasi-static rupture, and 5.5 kJm2 for dynamic rupture. We argue that\nrupture velocity determines damage zone width for slip up to a few mm, and that\nshear fracture energy \Γ increases with increasing rupture velocity.\n