Prehistoric damaging earthquake promoted the decline of "Heluo Ancient State" in Early China.

The emergence of the "Ancient State" is considered an important stage in the discourse on human civilizations. Based on its complex and hierarchical social structure, the Shuanghuaishu site of Henan Province is regarded as an "Ancient state", specifically the "Heluo Ancient State". The site is situated in the middle reaches of the Yellow River region and played a key role in prehistoric China. However, the reasons behind its decline are unclear. Here, we conducted an integrated investigation of the archaeological excavations and archaeoseismic analyses at the Shuanghuaishu site. We identified paleoseismic remains within paleo-artificial moats, which were formed owing to off-fault structures of soil liquefaction, hillslope landslides, and related ground fractures, along with shake-related wall disruption and building collapse in the residential zone. Charcoal dating was conducted to constrain the age for this earthquake event, which was determined to be approximately 5.0 cal kyr BP. Furthermore, based on the practical curve for earthquake-induced liquefaction, the preliminary estimate of the magnitude of this paleoseismic event is greater than M_s5.9–6.0. We propose that the Shuanghuaishu site experienced a recession after the earthquake event, which may have influenced the continuous development of the "Heluo Ancient State" as a regional center settlement. [ABSTRACT FROM AUTHOR]