2001年永胜6.0级地震的余震序列应力降研究

英文篇名：Study of the Stress Drop of Aftershock Sequence of M6.0 Yongsheng Earthquake in 2001
中文刊名：地震研究
英文刊名：Journal of Seismological Research
作者：秦嘉政 ; 邬成栋 ; 钱晓东
英文作者：Qin Jiazheng Wu Chengdong Qian Xiaodong (Earthquake Administration of Yunnan Province ; Kunming 650041 ; China)
中文关键词：地震序列 ; 地面峰值速度 ; 震源参数标度 ; 地震应力降 ; 永胜地震
英文关键词：earthquake sequence ; ground peak velocity ; scale of source parameters ; stress drop ; Yongsheng Earthquake
出版日期：2004-04-23
机构：云南省地震局,云南省地震局,云南省地震局昆明650041 ,昆明650041 ,昆明650041
年：2004
期：02
出版单位：地震研究

摘要

根据Haskell提出的一个统计不均匀随机震源ω -立方模型 ,导出了用震源参数估算地面运动峰值速度的量度 ,从而建立了地面运动峰值速度 (r·v)直接与震源参数的依赖关系 ,即 ,以地震矩、应力降作为标度律参数 ,预测的地面峰值速度按照M01 2 Δσ1 2 标度。对永胜地震近场数字地震记录的峰值速度参数资料的分析表明 ,这样的标度关系更适合对小地震的震源参数估算的统计研究。假定Q因子随频率线性变化的指数衰减项作为地震波传播距离的非弹性衰减 ,导出用地面运动峰值速度直接估算地震应力降Δσ的关系 :lg (r·v e-qr) =- 6 0 +0 5lgM0 +0 5lgΔσ ,测定了 2 0 0 1年永胜M6 0级地震近场数字地震台网观测的 1 0 0多次余震序列的地震应力降。结果给出 ,震级在 0 5 Based on the ω-cubic model which was proposed by Haskell to count the non-homogenous random source, a relation which uses the source parameters to estimate the peak velocity of ground is derived and the relation between the peak velocity and the source parameters is set up.Besides, taking seismic moment (M 0) and stress drop (Δσ)as the scaling parameters, the estimated peak velocity of ground(r·v) is scaled as M 0 1/2 Δσ 1/2 .This scaling relation is proved to be more suitable for the study of source parameters of small earthquakes when by the analysis of peak velocity of the digital earthquake recordings in the near field of Youngsheng Earthquake.Assuming that the Q-factor changes in a linear way with frenquency and this linear change can be regarded as the earthquake waves' non-elastic attenuation along with the propagation path of the seismic wave, the relation which is able to estimate the stress drop through peak velocity of ground can be derived as.using the relation,the stress drop of Yongsheng Earthquake sequence was calculated.The sequence contains over 100 aftershocks and it was recorded by the near-field digital seismic array station.The results show that the stress drop varies from 0 01 MPa to 4 2MPa when the magnitude (M L) ranges from 0 5 to 2 6.99 5% stress drops are no more than 1 0MPa and 60% stress drops are extra-low values (no more than 0 1MPa).In the whole sequence, the stress drop attenuates very fast.The low-stress state is in accordance with the weak-strength attenuation of the Yongsheng earthquake.The aftershock sequence reflects a low-energy rupture process.

引文

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