Figure 7

Comparison of the distributions of ensembles of torque variation (i) required upon NZ to explain the GNSS–observed Euler–vector change (in dark grey) and (ii) imparted to NZ by the interseismic buildup of stress preceding the 2010 Maule, 2014 Iquique, and 2015 Illapel earthquakes (in colours, including the torque variation resulting from their superimposition). The main map shows the distributions of torque-variation poles (contours show the regions where the most-recurrent 95% of poles fall, continents are in light grey), while the inset displays the distributions/ranges of torque-variation magnitude. In the inset, dashed-coloured lines show the range of torque-variation magnitudes obtained when considering the entire interseismic stress buildup phase. Instead, solid-coloured lines show the fraction of that would be built up during the period covered by GNSS observation if the interseismic stress grew linearly through time — calculated by multiplying the total interseismic torque-variation by the ratio between the 10–yr and the recurrence time of each considered earthquake (see main text for details). Grey histograms show the distributions of torque-variation magnitudes required to explain the NZ kinematic change, and are calculated using an average asthenosphere viscosity of \(10^{19}\) \(\mathrm {Pa \cdot s}\) (thin grey line), \(2 \times 10^{19}\) \(\mathrm {Pa \cdot s}\) (medium-thick grey line) or \(3 \times 10^{19}\) \(\mathrm {Pa \cdot s}\) (thick grey line). This figure has been produced partially using Generic Mapping Tools version 6⁷⁶.