摘要
2002年在浙江温州的珊溪水库发生了一系列水库诱发地震,其拐角频率明显小于同震级的构造地震。本文从二相介质理论出发,讨论了水库岩体在扩容、流体渗入饱和和强度弱化过程中波速和波速比的变化以及对拐角频率的影响。根据实验结果,当孔隙度为0.15,岩体弹性模量减小23%时,拐角频率可以减小约29%。由此解释了水库诱发地震拐角频率偏小主要是由裂隙发育和库水渗透扩散使地壳浅部岩体强度弱化引起的。因此拐角频率可以作为区别两者的一个依据。
In 2002,a reservoir induced earthquake sequence took place in Shanxi reservoir,Wenzhou city,Zhejiang province.The corner frequencies of the earthquakes were prominently less than that of tectonic earthquakes.Based on the theory of wave propagation in two phases medium,the variations of wave velocity, v_p/v_s ratio and the influence on corner frequency in the process of dilatancy-diffusion, saturation with water and strength weakness of rock mass are discussed.According to some experiment results if the porosity is 0.15 and the elasticity modulus of rock decreases 23%, the corner frequency can decrease about 29%.It indicates that the corner frequency of the reservoir-induced earthquake decreasing is caused by fracture growing and infiltration diffusion of water,which lead to the strength weakness of rock mass.Thus the corner frequence may be used as a criterion for distinguishing the reservoir-reduced earthquakes from the tectonic earthquakes.
出处
《西北地震学报》
CSCD
北大核心
2004年第4期315-321,共7页
Northwestern Seismological Journal
基金
.浙江省重点科研项目(991103263)
关键词
水库诱发地震
二相介质
岩体弱化
拐角频率
Reservoir-reduced earthquake
Two phases medium
Weakness of rock mass
Corner frequency
