Seismic Tectonic Environmengt and Synseismic geological Hazard Characteristics of Maerkang M6.0 Earthquake Swarm in the Western China
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摘要: 马尔康震群型地震构造背景复杂,同震地震灾害发育,研究地震的构造环境是分析预测地震危险性的基础,研究震群型同震地质灾害的分布规律及特征有利于揭示不同类型地震诱发地质灾害的差异性,可为地震诱发次生地质灾害防治和预测提供指导。本文基于马尔康6.0级震群型地震序列数据、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,探讨了马尔康6.0级震群的区域和深部构造环境、控制同震地质灾害的主要因素。研究认为:(1)马尔康6.0级震群型地震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黏滑型地震,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;(2)地震共诱发新增地质灾害隐患83处,导致在库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%;(3)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联动断裂、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。研究成果对于认识巴颜喀拉地块周边和内部的地震风险、潜在地震次生灾害的预测提供借鉴。Abstract: The tectonic background of the Markang earthquake swarms is complex, and the coseismic earthquake disasters are developed. Studying on the tectonic environment of earthquakes is the basis for analyzing and predicting earthquake risks. Studying on the distribution laws and characteristics of geological coseismic geological disasters of the earthquake swarms type is conducive to revealing the differences of geological disasters induced by different types of earthquakes, and could provide guidance for the prevention and prediction of secondary geological disasters induced by earthquake . Based on the seismic sequence data, regional tectonic environment research results, regional crustal deformation research data, and geological disaster data in the short term after the earthquake, this paper discussed the regional and deep tectonic environment of the Markang M6. 0 earthquake swarms and the main factors controlling the coseismic geological disasters. The research shows that: (1) the Markang earthquake swarm of magnitude 6.0 is a deep stick slip earthquake that occurred in the strong seismic gap on the secondary fault in the Bayan Har block with strong activity on the peripheral boundary, and multiple earthquakes with similar magnitudes may be the result of the secondary fault rupture of the Songgang fault and the successive rupture of the partition between them; (2) A total of 83 new geological hazards were induced by the earthquake, resulting in 106 more deformation at the hidden danger points of the reservoir, and many high level landslides and a series of earthquake cracked mountains. After the earthquake, the areas of the extremely high, high and medium risk geological hazards in Caodeng Township accounted for 1.62%, 4.80% and 12.37% respectively; (3) The control factors of coseismic geological disasters from primary to secondary are seismogenic fault and its linkage fault, earthquake magnitude and energy attenuation, terrain slope and height difference, rock mass structure and structural plane density. The intersection area of Songgang fault and Longriba active fault that caused the earthquake has a high risk of strong earthquakes in the future, and the risk of geological disasters around the earthquake generating fault and the fault with its linkage effect is high during earthquakes. The research results can provide reference for understanding the earthquake risk around and inside the Bayan Har block and predicting the secondary disasters in potential earthquakes.
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Key words:
- Markang earthquake /
- Earthquake swarms /
- Seismotectonics /
- Songgang fault /
- Coseismic geological hazard
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