Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 48; pp. 18931 - 18936
• Main Authors: Lu, Xiao, Lapusta, Nadia, Rosakis, Ares J
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 27.11.2007; National Acad Sciences
• Series: From the Cover
• Subjects: Earthquakes; Experiment design; Experiments; High speed photography; Nucleation; Particle velocity; Physical Sciences; Plate tectonics; S waves; Seismology; Sliding; Speed; Traumatic ruptures; Velocity
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0704268104

Theoretical studies have shown that the issue of rupture modes has important implications for fault constitutive laws, stress conditions on faults, energy partition and heat generation during earthquakes, scaling laws, and spatiotemporal complexity of fault slip. Early theoretical models treated earthquakes as crack-like ruptures, but seismic inversions indicate that earthquake ruptures may propagate in a self-healing pulse-like mode. A number of explanations for the existence of slip pulses have been proposed and continue to be vigorously debated. This study presents experimental observations of spontaneous pulse-like ruptures in a homogeneous linear-elastic setting that mimics crustal earthquakes; reveals how different rupture modes are selected based on the level of fault prestress; demonstrates that both rupture modes can transition to supershear speeds; and advocates, based on comparison with theoretical studies, the importance of velocity-weakening friction for earthquake dynamics.