Propagation of large earthquakes as self-healing pulses or mild cracks.

Valere R. Lambert, Nadia Lapusta, & Stephen M. Perry

Published March 10, 2021, SCEC Contribution #10085

Observations suggest that mature faults host large earthquakes at much lower levels of stress than their expected static strength. Potential explanations are that faults are indeed quasi-statically strong but experience dramatic weakening during earthquakes, or that faults are persistently weak, e.g., due to fluid overpressure. Here, we use numerical simulations to show that self-healing pulses, which occur on quasi-statically strong but dynamically weak faults, result in much larger radiated energy than inferred for most natural events, whereas crack-like ruptures on persistently weak faults are consistent with most seismological observations. The larger radiated energy of self-healing pulses is consistent with limited observations from crustal faults. These findings suggest that either large earthquakes rarely propagate as self-healing pulses, with potential differences between tectonic settings, or their radiated energy is substantially underestimated, raising questions about earthquake physics and expected shaking from large earthquakes.

Lambert, V. R., Lapusta, N., & Perry, S. M. (2021). Propagation of large earthquakes as self-healing pulses or mild cracks.. Nature, 591, 252–258.