Sulawesi lies within the complex zone of interaction between the Australian, Pacific, Philippine and Sunda Plates in which many small microplates are developed. The main active structure onshore in the western part of Central Sulawesi is the left-lateral NNW-SSE Palu-Koro strike-slip fault that forms the boundary between the North Sula and Makassar blocks and was responsible for the destructive Palu earthquake in 2018. According to the interpretation of GPS data, the Makassar block is currently rotating anticlockwise, with its northwestern margin showing convergence with the Sunda block across the Makassar Strait. The main structure in that part of Sulawesi is the offshore, north–south trending, moderately east-dipping Makassar Thrust, also known as the Majene Thrust. The GPS data also support the presence of a seismically "locked" fault in the Makassar Strait. Seismic reflection data from the Makassar Strait support the presence of active thrusting west of the Makassar block. The Majene/Kalosi fold and thrust belt is exposed onshore between Majene and Mamuju. The northern part of the Makassar Strait is interpreted as a foreland basin, with its subsidence caused by the loading of this active thrust belt.