Characteristics of geological hazards induced by the Menyuan M6.9 earthquake
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1.Key Laboratory of Loess Earthquake Engineering of China Earthquake Agency & Gansu Province, Lanzhou 730000, Gansu, China;2.Gansu Earthquake Agency, Lanzhou 730000, Gansu, China;3.Qinghai Earthquake Agency, Xining 750000, Qinghai, China

Clc Number:

P319.56

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    Abstract:

    The Menyuan M6.9 earthquake occurred on January 8, 2022, induced many kinds of co-seismic geo-hazards, i.e., collapses, landslides, sand liquefaction, and ground fissures. Based on the field investigation results, the distribution and characteristics of various types of geological disasters induced by the M6.9 earthquake were obtained in this paper. Besides, the reasons for the undeveloped seismic geo-hazards were analyzed, and the long-term effects of seismic geo-hazards were predicted. The results showed that the geo-hazards induced by the M6.9 earthquake are mainly distributed near the epicenter. The collapses and rockfalls are not big. Most of the landslides are rock landslides, which are dominated by the sliding of moraine and surface rock and soil. Due to the freezing of surface soil and the dissipation of pore water pressure, the liquefaction of saturated sand is beaded along narrow ground fissures, and the ejecta is mostly silty and fine sand. Four sinistral oblique surface rapture zones and a large number of ground fissures are formed in the meizoseismal area. The barrier effect of fault fracture zone on strong motion, thin overburden layer, and freezing of surface soil may cause the undevelopment of seismic geo-hazards. A large number of ground fissures generated by the earthquake weaken the stability of slopes and accumulation bodies, which may induce landslides under the coupling action of concentrated rainfall and freezing-thawing cycles. In addition, loose deposits in gully beds generated by collapses and landslides may increase the risk of debris flow in earthquake-affected areas.

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History
  • Received:February 17,2022
  • Online: April 19,2022
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