The mudflow disaster induced by the Ms 6.2 Jishishan earth-quake reproduces the prehistorical catastrophes in the Lajia Ruins
The Lajia Ruins,a large Neolithic settlement of the Qijia Culture(4200-3600 a BP),is located on the second terrace of the Yellow River within the Guanting Basin,Minhe County,Qinghai Province.Archaeological excavations have revealed 32 human skeletons in a variety of postures resting on the dwelling floors,as well as the earliest millet noodles in the world.These discoveries present startlingly unusual scenes that suggest dramatic and miserable prehistoric catastrophes in the ruins.And then,these ruins were selected as one of China's Top 10 New Archaeological Discoveries of 2001.Scholars have put forward various views about the causes of the collapse of the prehistorical settlement of the Qijia Culture in the ruins.One view is that an earthquake first caused the houses to collapse,and that an extreme rainstorm flood event of the Yellow River then completely destroyed the prehistoric settlement.Another view is that the paleo-earthquake led to a massive landslide damming event in the Jishixia Gorges of the Yellow River,and that after six to nine months,a tremendous outburst flood with a peak discharge of ca.40× 104 m3/s resulted in the collapse of the prehistorical settlement.However,our team determined that the prehistoric settlement was destroyed at ca.3850 a BP by a major paleo-earthquake as the first hitting,immediately followed by large-scale rainstorm-induced flashfloods and mudflows from tributary gullies.Earthquakes and their secondary disasters often cause great losses for human society.On December 18,2023,a Ms 6.2 earthquake struck Jishishan County,Gansu Province,killing 151 people(117 in Gansu Province and 34 in Qinghai Province),injuring 980,and damaging infrastructure such as houses and roads.Caotan and Jintian villages in Minhe County within the Guanting Basin suffered severe secondary disasters such as landslides and mudflows.Several meters of mudflow deposits buried residents,houses,and roads,causing considerable problems for rescue operations and attracting wide attention.The Lajia Ruins and Caotan and Jintian villages are all located east of the Lajishan Fault and are only 4.5 km apart.This paper presents a comparative analysis that provides a realistic case for a deep understanding of the occurrence process of the prehistoric catastrophes in the Lajia Ruins.The results indicate that the geological,geomorphic,and other environmental backgrounds of these two catastrophes and the scenes of these mudflow disasters caused by earthquakes,were very similar.However,in the geological disaster associated with Caotan and Jintian villages,the Ms 6.2 earthquake first triggered the landslide,and the landslide deposits consisting of Malan loess mixed with paleo-flashflood and paleo-mudflow deposits then became the material source of the mudflow.Therefore,the cause and material source of the modern mudflow disaster in Caotan and Jintian villages differed from those of the paleo-mudflow disaster in the Lajia Ruins.
Ms 6.2 Jishishan earthquakeCaotan and Jintian villagesLajia Ruinsmudflow disaster
张玉柱、沈铭健、郭永强、孟兴民、李亚军、钟宁、陈发虎
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西北大学城市与环境学院,陕西省地表系统与环境承载力重点实验室,西安 710127
中国科学院青藏高原研究所,青藏高原地球系统与资源环境全国重点实验室,北京 100101
中国科学院大学资源与环境学院,北京 100049
中国科学院、水利部成都山地灾害与环境研究所,成都 610041
兰州大学西部环境教育部重点实验室,兰州 730000
兰州大学地质科学与矿产资源学院,兰州 730000
中国地质科学院地质力学研究所,自然资源部活动构造与地质安全重点实验室,北京 100081
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Ms 6.2 Jishishan earthquake Caotan and Jintian villages Lajia Ruins mudflow disaster
万方数据
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