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小震群朝汶川主震初始破裂点撕裂的震兆图像
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作者 魏娅玲 蔡一川 苏金蓉 《大地测量与地球动力学》 CSCD 北大核心 2014年第5期17-20,24,共5页
为了解汶川M8.0地震临近前震源初始破裂区小震群活动特征,重新确定研究区域地震震源位置,并求解震前都江堰两次较大有感地震震源机制。结果显示:1)M8.0地震临近前,震源初始破裂区附近出现地震活动增多、小震群分布成带现象;地震条带东... 为了解汶川M8.0地震临近前震源初始破裂区小震群活动特征,重新确定研究区域地震震源位置,并求解震前都江堰两次较大有感地震震源机制。结果显示:1)M8.0地震临近前,震源初始破裂区附近出现地震活动增多、小震群分布成带现象;地震条带东南端起始都江堰聚源镇,总体以约西42°北往西北延伸至都江堰龙溪镇,长约20 km;2)地震条带东南端地震震源深度较浅,均在地表之下10 km以内,随着时间推移,小震活动自东南向西北扩展至紫坪铺水库和汶川主震初始破裂区,发生地震的部位也向深部迁移约7 km;3)2月14日ML3.7地震震源机制解滑动角为93°,北东盘垂直向下运动,与小震群扩展图像显示的汶川主震初始破裂点附近下盘下插现象一致,表明汶川主震初始破裂点在震前已被撕裂,为主震能够从此处开始破裂准备好了必要条件;4)2月28日ML3.8地震不仅已经位于龙门山中央主断裂,而且得到与汶川主震比较接近的震源机制解,两者应力状态一致,应属于直接前震。 展开更多
关键词 汶川M8.0地震 小震群活动特征 地震条带 初始破裂区 震源机制解
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Research on the Activity Characteristics of Small Earthquake Swarms in the Muli Area of Sichuan Province
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作者 Cai Yichuan Dai Shigui Wei Yaling 《Earthquake Research in China》 CSCD 2016年第2期215-223,共9页
In this article,we relocated the seismic source location of the earthquakes in the Muli area of Sichuan,inverted the focal mechanism of the larger earthquakes and analyzed the relationship between the water level of t... In this article,we relocated the seismic source location of the earthquakes in the Muli area of Sichuan,inverted the focal mechanism of the larger earthquakes and analyzed the relationship between the water level of the Jinping reservoir and the frequency of the earthquake swarm. The results show that:( 1) The epicenters of the relocated small earthquake swarms are distributed in a seismic zone,and the earthquake focal depths were in the range of 0- 12 km.( 2) By analyzing the earthquake swarm spatial distribution,we found that the swarms were generated by one branch fault on the west of Xiaojinhe fault.( 3) The focal mechanism of the three earthquakes with magnitude greater than 4. 0 is significantly different,with the shallow source thrust events affected by vertical stress,and the strike-slip events are related to regional stress tectonic activity. 展开更多
关键词 Earthquake swarm activities Seismic zone Double difference locationmethod Focal mechanism
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