Effect of off-fault low-velocity elastic inclusions on supershear rupture dynamics

Xiao Ma, A. E. Elbanna

Research output: Contribution to journalArticlepeer-review


Heterogeneous velocity structures are expected to affect fault rupture dynamics. To quantitatively evaluate some of these effects, we examine a model of dynamic rupture on a frictional fault embedded in an elastic full space, governed by plane strain elasticity, with a pair of off-fault inclusions that have a lower rigidity than the background medium. We solve the elastodynamic problem using the Finite Element software Pylith. The fault operates under linear slip-weakening friction law. We initiate the rupture by artificially overstressing a localized region near the left edge of the fault. We primarily consider embedded soft inclusions with 20 per cent reduction in both the pressure wave and shear wave speeds. The embedded inclusions are placed at different distances from the fault surface and have different sizes. We show that the existence of a soft inclusion may significantly shorten the transition length to supershear propagation through the Burridge-Andrews mechanism. We also observe that supershear rupture is generated at pre-stress values that are lower than what is theoretically predicted for a homogeneous medium. We discuss the implications of our results for dynamic rupture propagation in complex velocity structures as well as supershear propagation on understressed faults. Published by Oxford University Press on behalf of The Royal Astronomical Society 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Original languageEnglish (US)
Pages (from-to)664-677
Number of pages14
JournalGeophysical Journal International
Issue number1
StatePublished - Aug 4 2015


  • Earthquake dynamics
  • Wave propagationcover-date

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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