从丽江7.0级地震前的地壳形变探讨地震短临前兆特征
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摘要
本文讨论了“拉疏隆起-压缩凹陷”——不稳孕震体特性和形成机理;通过对丽江7.0级地震前滇西地区的地壳形变资料,进一步证实本区有强震发生及发震的地点;讨论了孕震体由“僵硬闭锁”到“不同步加速”、“分离反向”、“不均匀掀斜”、再度“停滞平静”、甚至“颤抖”等多态不稳变化,是地壳形变的短临地震前兆特征;根据震前“拉疏隆起-压缩凹陷”的范围大小、幅度值及岩层的弹性应变,可近似计算震级的大小。
This paper discusses the features and formation mechanism of seismogenic structure, i. e. "extensional uplift and compressive depression". Analysis of the data of crustal deformation data of western Yunnan before the Ms = 7. 0 earthquake in Lijiang ascertains that there will be strong earthquakes in this region and evendetermines the exact site of the earthquakes. It is suggested that the impending and short-term earthquake precursory features of crustal deformation are various unstable changes, from "Stiff locking" of the seismogenic structure through "asynchronous acceleration", "separation inversion", and "uneven tilting" to "stagnation and calmness" or even to "vibration". According to the size and amplitude of the "Compressive depression-extensional uplift" and the elastic strain of rocks observed before the earthquake, the earthquake magnitude can be approximately calculated.
This paper discusses the features and formation mechanism of seismogenic structure, i. e. "extensional uplift and compressive depression". Analysis of the data of crustal deformation data of western Yunnan before the Ms = 7. 0 earthquake in Lijiang ascertains that there will be strong earthquakes in this region and evendetermines the exact site of the earthquakes. It is suggested that the impending and short-term earthquake precursory features of crustal deformation are various unstable changes, from "Stiff locking" of the seismogenic structure through "asynchronous acceleration", "separation inversion", and "uneven tilting" to "stagnation and calmness" or even to "vibration". According to the size and amplitude of the "Compressive depression-extensional uplift" and the elastic strain of rocks observed before the earthquake, the earthquake magnitude can be approximately calculated.
引文
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10 谢觉民,Chi-Yu King.中美断层形变研究进展及异同比较.大地形变测量,1994,10(1/2) :42．
11 秋原幸男.GPS对大地测量学的影响.见:GPS技术研究新进展.天津科学技术出版社,1996．
2 周友华.地壳形变与地震探讨.华北地震科学.1995,13(4) :47．
3 周友华.构造地震孕育及应力传递集中机制的研究.见:中国地震学会第六次学术大会论文摘要集.北京:地震出版社,1996,111．
4 张兴华,宋金玲,王琼伟,邵德盛.云南地壳形变与丽江7． 0级地震.地震研究,1997,20(1) :72．
5 陈颙.地壳岩石的力学性能--理论基础与实验方法.北京:地震出版社,1988． 158．
6 周光全,张建国,周瑞琦,昊伯黔,王桂兰.丽江7． 0级地震的地震地质构造背景分析.地震研究,1997,20(1) :92．
7 郭增建,马宗晋,林伟凡,刘庆民.中国特大地震研究.北京:地震出版社,1988．
8 马宗晋,傅征祥,张郢珍,江成民,张国民,刘德富.1966～1976年中国九大地震.北京:地震出版社,1982．
9 张建国,周瑞琦,吴伯黔,周光全.丽江7． 0级地震地表破裂与形变特征.地震研究,1997,20(1) :58．
10 谢觉民,Chi-Yu King.中美断层形变研究进展及异同比较.大地形变测量,1994,10(1/2) :42．
11 秋原幸男.GPS对大地测量学的影响.见:GPS技术研究新进展.天津科学技术出版社,1996．
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