Tectonic setting of the North Island of New Zealand. An overview of New Zealand is shown at the top right, along with the plate boundary between the AUS and PAC. In the main figure, the black arrow shows the plate velocity of the PAC relative to the AUS, and the purple arrows show the orthogonal convergence rates when accounting for the clockwise block rotation of the forearc region (Wallace et al. ; Nicol and Wallace ). The purple ellipse shows the pole location used for the block rotation. Gray lines represent the plate contours by Ansell and Bannister (). The brown line demarcates the location of the cross section used in numerical modeling of the thermal structure. Note that the wedge-shaped volcanic region is also shown. Colored dots represent the observed heat flow data (Global Heat Flow Database compiled by Pollack et al.  and Townend ; Allis et al. ). Color scale is shown at right bottom of the figure. At three onshore coastal regions (southern, northern, and northernmost coastal region), the mean and standard deviation values of observed heat flow data are indicated.