Timing of Holocene paleo-earthquakes along the Langshan Piedmont Fault in the western Hetao Graben, North China: Implications for seismic risk

• We examined the paleoseismicity of the Langshan Piedmont Fault (LPF).
• 4 paleo-earthquakes with repeat time of ~ 2450 yr occurred in the past ~ 9810 yr.
• The most recent earthquake (MRE) probably took place in the last ~ 1880 yr.
• Rupture of the entire LPF could source an earthquake of Mw 7.8.

Geological evidence and precise age constraints for faulting events during the Holocene are vital for assessing the seismic potential of active faults, especially in regions lacking instrumental and historical records of earthquakes. For this study, we constrained the timing and recurrence intervals of Holocene paleo-earthquakes along the ~ 160-km-long NE–SW-trending Langshan Piedmont Fault (LPF), which forms the NW boundary of the Hetao Graben, North China. The results of outcrop observations and radiocarbon dating reveal that: 1) at least four surface-rupturing earthquakes occurred during the past ~ 9810 yr with an average recurrence interval of ~ 2450 yr; 2) the most recent earthquake (MRE) probably took place within the past ~ 1880 yr; 3) rupturing of the entire LPF could produce an earthquake of Mw ~ 7.8, posing a significant seismic risk in the region of the western Hetao Graben. We suggest that more detailed paleoseismological studies on the active LPF are needed, in order to have a better understanding of its seismogenic behavior.