从丽江7.0级地震前的地壳形变探讨地震短临前兆特征

Impending and Short-Term Precursory Features of Earthquakes Studied in Light of Crustal Deformation before the Earthquake of Ms=7. 0 in Lijiang

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.