Crustal deformation in the central and southern Ryukyu Arc estimated from GPS data

Abstract

Deformation of the Ryukyu Arc in the period 1999–2001 was investigated on the basis of GPS data for horizontal velocity. The results show that deformation of the Ryukyu Arc is divided into three tectonic blocks, with all counter-clockwise rotation rates of between 18 and 195 nrad/yr. Extensional strain along the Ryukyu Arc is observed in all three blocks, being largest in the southwestern Ryukyu Arc. This suggests that southward bending of the arc occurs in the southwest associated with the arc–continent collision in Taiwan, resulting in clockwise block rotation of the Taiwan–Ryukyu junction. Thus, bending of the Ryukyu Arc appears to be caused by collision of the Luzon Arc with the Eurasian plate, and is likely to contribute to rifting of the Okinawa Trough.