Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

264 PATA Days 2024 Fig. 2: High-resolution topography from drone image and 1905 rupture mapping with the location of the trenches. Images b and d are field views of the trench site. geomorphic landforms to evaluate a slip-rate of 0.38 mm/yr over a period of ~27 kyr. We excavated two fault-perpendicular trenches along the Tsetserleg fault, which allow identifying a minimum of three paleo-events. The penultimate earthquake may have developed within a doublet sequence similar to the 1905 series. However, considering the paleo-events identified since 17 ka, the average recurrence time along the Tsetserleg fault appears to be 2.5 times longer than the earthquake sequence on the Bulnay fault. Thus, we show that complex fault systems can be characterized by significant variation of the rupture patterns over successive seismic cycles and that the almost synchronous rupture of 4 large faults in Mongolia might not correspond to a systematic pattern.