A top-to-down migration of slip during the 2016 Kaikōura Earthquake
Vasiliki Mouslopoulou  1, 2, *@  , Vasso Saltogianni  1, *@  , Andrew Nicol  3@  , Onno Oncken  1@  , John Begg  4@  , Andrey Babeyko  1@  , Simone Sesca  1@  , Marcos Moreno  1, 5@  
1 : German Research Centre for Geosciences - Helmholtz-Centre Potsdam
Telegrafenberg, 14473 Potsdam -  Germany
2 : National Observatory of Athens
Lofos Nymphon -  Greece
3 : University of Canterbury
Christchurch -  New Zealand
4 : GNS Science
Lower Hutt -  New Zealand
5 : Universidad de Concepción
Víctor Lamas 1290, Concepción -  Chile
* : Corresponding author

The 2016 Mw7.8 Kaikōura Earthquake was an exceptionally composite earthquake, rupturing at least 17 surface-breaking faults at the southern-end of the Hikurangi margin. This earthquake provides an excellent opportunity to examine slip-transfer between faults located at different tectonic domains of a subduction system. Numerical modeling, conditioned by a multitude of far-field (GPS) and near-field (marine-biota, lidar and earthquake relocation) data, captures a rare snapshot of slip-transfer between upper-plate faults and the subduction-thrust. Specifically, we find a predominance (c. 80%) of slip on upper-plate faults and minor triggered-slip on the plate-interface. The Kaikōura earthquake suggests that these steep near-surface faults provide a key mechanism in the transfer of plate motion at the termination of a subduction margin and may represent an important seismic/tsunami hazard.

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