The Shanxi Rift System or Fen–Wei Rift System is a zone of active extensional tectonics that forms the eastern margin of the Ordos Block in northern China. The zone extends for at least 900 km (560 mi) and runs south-southwest to north-northeast. The individual rift basins that make up the rift system have an overall en echelon geometry, consistent with a right lateral sense of strike-slip displacement across the zone. The basins contain a thick sedimentary sequence of Neogene age, which ranges from 2.0 to 3.8 km in thickness. The rift system is continuous with the Weihe Basin to the southwest, which became active during the Paleogene. Rupture of the major normal faults that bound the Weihe and Shanxi rift basins has caused many large and damaging historical earthquakes, including the 1303 Hongdong, 1556 Shaanxi, 1626 Lingqiu, 1695 Linfen and 1815 Pinglu events.