Earthquake Damage Patterns Resolve Complex Rupture Processes.

Fracture damage patterns around faults induced by dynamic earthquake rupture are an invaluable record to clarify the rupture process on complex fault networks. The 2016 Mw 7.8 Kaikōura earthquake in New Zealand has been reported as one of the most complex earthquakes ever documented that ruptured at least 15 crustal faults. High‐resolution optical satellite image displacement maps provide distinctive profiles of displacement across the faults and help visualize the off‐fault damage pattern. They are combined with field observation and coupled with a numerical tool that captures the dynamics of the rupture and simultaneous activation of off‐fault damage to allow the determination of the most likely rupture scenario. This study demonstrates that complex rupture processes can be explained in a rather simple way via a synergetic combination of state‐of‐the‐art observation and first principle physics‐based numerical modeling of off‐fault damage. Plain Language Summary: In a first‐of‐its‐kind work, we combine optical image correlation at a resolution never achieved before (1.8‐m ground resolution), field observations, and a unique dynamic rupture simulation tool, including off‐fault deformation, to unravel, beyond doubt, part of the Kaikōura rupture process. We show that matching observed off‐fault deformation pattern with rupture simulation helps easily identify the earthquake rupture path to propose a kinematically simple earthquake scenario. Thus, this work shows that when building models of seismic hazard, like in Southern California, systematic consideration of off‐fault damage patterns for past events would help understand earthquake scenario and to model future events. Hence, this presents a great potential to narrow down the multitude of rupture scenarios along complex fault networks that need to be considered in seismic hazard model assessment. Key Points: Matching observed off‐fault deformation pattern with rupture simulation helps identify the earthquake rupture pathSystematic consideration of off‐fault damage patterns for past events would help understand earthquake scenario and to model future eventsThis presents a great potential to narrow down the multitude of rupture scenario on complex fault system [ABSTRACT FROM AUTHOR]