CALCULATION OF THE CO‐SEISMIC DEFORMATION AND STRESS CHANGES OF THE KAIKOURA Mw7.8 EARTHQUAKE, NOV 13, 2016

Abstract

AbstractOn 13 November, 2016, an Mw7.8 earthquake occurred in Kaikoura, northern South Island, New Zealand. The Mw 7.8 earthquake caused strong surface deformation, massive landslides and tsunami. Based on the fault slip model released by United States Geological Survey, the co‐seismic deformation and stress changes by Kaikoura Mw7.8 earthquake were computed with the global heterogeneous ellipsoid Earth model and high precision topography. The preliminary results show that the hanging wall of the Mw7.8 earthquake uplifted to the northeast, while the footwall subducting southwest. The co‐seismic deformation caused by this earthquake is up to several centimeters from Kaikoura to Campbell and the capital city of Wellington. The maximum co‐seismic horizontal displacement is about 1.2 m whereas the vertical is about 1.1 m. Although the accumulated strain along seismogenic faults had been released by this earthquake, the compressional force at the both ends of the seismogenic faults was increased due to co‐seismic stress changes and the maximum value of the co‐seismic stress changes reaches the order of MPa. The Coulomb failure stress changes are also up to MPa that are concentrated in the vicinity of epicenter. At the same time, the risk for NE‐SW dextral slip faults increases due to the co‐seismic shear stress. We also calculated the Coulomb Failure Stress changes in the North Island and South Island with local fault systems respectively. Our results show that Coulomb failure stress changes are positive in both regions, which means subsequent earthquakes are possible.