Evidence of a Supershear Transition Across a Fault Stepover

H. L. Kehoe, E. D. Kiser

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Supershear earthquakes, propagating faster than the Earth's shear wave velocity, can generate strong ground motion at distances far from the ruptured fault. Despite the hazards associated with these earthquakes, the exact fault properties that govern their occurrence are not well constrained. Although early studies associated supershear ruptures with simple fault geometries, recent dynamic rupture models have revealed a supershear transition mechanism over complex fault geometries such as fault stepovers. Here we present the first observation of a supershear transition on a fault stepover system during the 2017 Mw 7.7 Komandorsky Islands earthquake. Using a high-resolution back-projection technique, we find that the earthquake's rupture velocity accelerates from 2.1 to 5.0 km/s between two offset faults, demonstrating the viability of a new supershear transition mechanism occurring in nature. Given the fault complexity of the Earth's transform plate boundaries, this result may improve our understanding of supershear rupture processes and their associated hazards.

Original languageEnglish (US)
Article numbere2020GL087400
JournalGeophysical Research Letters
Issue number10
StatePublished - May 28 2020


  • Aleutian
  • back projection
  • rupture
  • step over
  • supershear
  • transform

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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