Bounds on geologically current rates of motion of groups of hot spots

It is widely believed that groups of hot spots in different regions of the world are in relative motion at rates of 10 to 30 mm a −1 or more. Here we present a new method for analyzing geologically current motion between groups of hot spots beneath different plates. In an inversion of 56 globally distributed, equally weighted trends of hot spot tracks, the dispersion is dominated by differences in trend between different plates rather than differences within plates. Nonetheless the rate of hot spot motion perpendicular to the direction of absolute plate motion, v perp , differs significantly from zero for only 3 of 10 plates and then by merely 0.3 to 1.4 mm a −1 . The global mean upper bound on | v perp | is 3.2 ± 2.7 mm a −1 . Therefore, hot spots move slowly and can be used to define a global reference frame for plate motions. We propose a new method for estimating the motion of groups of hot spots using relative plate velocities and the trends of hot spot tracks Motion differs from zero for only 3 of 10 plates; nominal speeds: 1.3–3.9 mm a −1 , lower bounds: 0.3–1.4 mm a −1 , and upper bounds 2.3–6.3 mm a −1 Rates of motion between groups of hot spots thus are much lower than 10 mm a −1 to 30 mm a −1 or more as currently assumed by many researchers