Rapid rotations about a vertical axis in a collisional setting revealed by the Palu Fault, Sulawesi, Indonesia

Global Positioning System (GPS) measurements from 1992 to 1995 indicate that 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 currently has stored enough strain to produce a Mw>7 earthquake. The Palu and other nearby faults accommodate rapid clockwise rotation of nearly 4°/Ma of E Sulawesi relative to eastern Sunda. The rotation of east Sulawesi transfers E-W shortening between the Pacific and Eurasian plates to N-S subduction of the Celebes Basin beneath Sulawesi.

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