Fig. 1

a Tectonic setting of the study region. The dashed lines represent the plate boundary (Bird 2003). The arrow denotes the plate motion of the Pacific plate relative to the fixed Australia plate in NUVEL 1A (DeMets et al. 1994). The star marks the mainshock epicenter (Lanza et al. 2019). b Seismotectonic summary of the study region of the 2016 Kaikoura earthquake. The left and right beach ball shows the obtained total moment tensor and the Global Centroid Moment Tensor (Dziewonski et al. 1981; Ekström et al. 2012) for the mainshock, respectively. Black dots represent aftershocks during the week after the mainshock (Lanza et al. 2019). Gray, orange, blue, and green lines indicate surface ruptures of the 2016 Kaikoura earthquake from the New Zealand Active Faults Database (Langridge et al. 2016). The black line represents the assumed model plane. Background contours display topography/bathymetry (Mitchell et al. 2012). HmF–Humps fault zone, CCF–Conway-Charwell fault, MF–Manakau fault, UKF–Upper Kowhai fault, JT–Jordan Thrust, PF–Papatea fault, KF–Kekerengu fault, NF–Needles fault