Island arc curvature, velocity of convergence and angle of subduction

We report data on the curvature RC, rate of subduction v c and slab dip α for 28 convergent boundary segments of oceanic plates. Slowly converging plates (v c < 5 cm/yr) are associated with arcs having RC < 10°, while more rapidly converging plates produce arcs with RC ranging from 10° to greater than 90°. This provides a way of estimating former convergence rates of extinct arcs. Slab dip α is independent of v c for v c < 10 cm/yr; the inverse relation between α and v c proposed by Luyendyk (1970) is not substantiated by our larger data set. Slab dip and arc curvature are not correlated.