Geological and geomorphic evidence for activity of the Mengzi fault along the southeastern margin of the Tibetan Plateau

•The geometric distribution and activity of the Mengzi fault has been studied.•The horizontal slip rate of the fault has been obtained via the offset gullies and terraces.•Three paleo-events since 30–40 ka BP have been observed, with a 10-ka major earthquake recurrence period.•The Mengzi fault plays an important role in the adjustment of the large slip rate loss for the southern Xiaojiang fault.