摘要
为了揭示震群型同震地质灾害的分布规律和特征,理清不同类型地震诱发地质灾害的差异性,进一步认识巴颜喀拉地块周边和内部的地震风险,从而高效指导地震诱发次生地质灾害预测与防治工作,文章以2022年马尔康M_(S)6.0震群同震地质灾害为研究对象,通过对震群序列数据、区域构造环境研究成果、区域地壳形变研究数据、震后短期内的地质灾害数据等进行系统分析研究,揭示马尔康M_(S)6.0震群的区域和深部构造环境、同震地质灾害的主控因素。结果表明:马尔康M_(S)6.0震群是发生在周缘边界活动性极强的巴颜喀拉地块内部次级断裂上强震空区内的深部粘滑型地震,多次震级相近的地震可能是由于松岗断裂的次级断裂破裂和之间的隔堤相继破裂的结果;地震新增地质灾害隐患83处,导致地质灾害隐患点变形加剧106处,并诱发了多处高位滑坡和系列震裂山体,震后震中草登乡地质灾害极高、高、中风险区面积分别占比1.62%、4.80%和12.37%;地震诱发同震地质灾害的控制因素由主到次为发震断裂及其关联断裂、地震震级及能量衰减、地形坡度及高差、岩体结构及结构面密度。此次发震的松岗断裂与龙日坝活动断裂交切区未来强震风险高,发震断裂及与其有联动效应的断裂周边在地震时发生地质灾害风险高。
[Objective]This study aims to reveal the distribution patterns and characteristics of co-seismic geological hazards in earthquake swarms,clarify the differences in induced geological hazards by different types of earthquakes,further understand the seismic risks around and within the Bayan Har Block,and provide efficient guidance for the prediction and prevention of secondary geological hazards induced by earthquakes.[Methods]We take the co-seismic geological hazards of the Maerkang M_(S)6.0 earthquake swarm in 2022 as the research focus.Through systematic data and results analysis on earthquake swarm sequence,regional tectonic environment,regional crustal deformation,and postearthquake short-term geological hazard,the regional and deep structural environment of the Maerkang M_(S)6.0 earthquake swarm and the main controlling factors of co-seismic geological hazards are revealed.[Results]The results show that the Maerkang M_(S)6.0 earthquake swarm is a deep-seated sticky-slip earthquake that occurred on a secondary fault in the active strong earthquake zone within the Bayan Har block,a region with extremely strong peripheral boundary activity.The earthquakes with similar magnitudes may be the result of ruptures of secondary faults of the Songgang fault and the successive ruptures of the barriers between them.The earthquake has resulted in 83 newly discovered geological hazard risks,exacerbating deformation in 106 existing hazard spots and triggering multiple high-altitude landslides and a series of fractured mountain slopes.The areas of extreme,high,and medium geological hazard risk in Caodeng Town,the epicenter area after the earthquake,account for 1.62%,4.80%,and 12.37%,respectively.The occurrence of secondary geological hazards following earthquakes exhibits a positive correlation with the earthquake magnitude,with the number increasing linearly as the magnitude rises.[Conclusion]The significant differences in the GPS horizontal velocity field and vertical velocity field on both sides of the Darlag–Songgang–Fubianhe fault zone are key factors contributing to the activity of this fault and triggering the recent earthquake.The main controlling factors of co-seismic geological hazards induced by earthquakes are,from primary to secondary,the ruptured fault and its associated faults,seismic magnitude and energy attenuation,terrain slope and altitude difference,and rock mass structure and density of structural surfaces.[Significance]This study predicts a high risk of future strong earthquakes in the intersection area of the Songgang fault,which triggered this earthquake,and the Longriba active fault.The surrounding area of the seismogenic fault and its associated faults are at a high risk of geological hazards during earthquakes.The findings provides a reference for predicting and controlling the risk of co-seismic geological hazards in this area.
作者
孙东
覃亮
蒙明辉
杨涛
章旭
胡骁
SUN Dong;QIN Liang;MENG Minghui;YANG Tao;ZHANG Xu;HU Xiao(Sichuan Geological Environment Survey and Research Center,Chengdu 610081,Sichuan,China;Sichuan Province Engineering Technology Research Center of Geohazard Prevention,Chengdu 610081,Sichuan,China;Sichuan Huadi Construction Engineering CO.LTD.,Chengdu 610081,Sichuan,China)
出处
《地质力学学报》
CSCD
北大核心
2024年第3期443-461,共19页
Journal of Geomechanics
基金
四川省自然科学基金项目(2023NSFSC0784)
四川省科技计划项目(2023YFS0435)。
关键词
马尔康地震
地震构造
松岗断裂
同震地质灾害
青藏高原东缘
巴颜喀拉地块
Maerkang earthquake
seismotectonics
Songgang fault
coseismic geological hazard
eastern margin of the Tibetan Plateau
Bayan Har block
