Rapid rotations about a vertical axis in a collisional setting revealed bythe Palu fault, Sulawesi, Indonesia

Global Positioning System (GPS) measurements from 1992 to 1995 indicate tha t the left-lateral Palu fault in central Sulawesi slips at a rate of 38+/-8 mm/a with a locking depth between 2 and 8 km. From the measured slip rate and the historic seismicity of the fault, we estimate that the Palu fault c urrently has stored enough strain to produce a M-w>7 earthquake. The Palu a nd other nearby faults accommodate rapid clockwise rotation of nearly 4 deg rees/Ma of E Sulawesi relative to eastern Sunda. The rotation of east Sulaw esi transfers E-W shortening between the Pacific and Eurasian plates to NS subduction of the Celebes Basin beneath Sulawesi.