【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 <ML<2 6级的范围内 ,地震应力降为 0 0 1～ 4 2MPa ,余震序列中有99 5 %的地震应力降小于 1 0MPa,一个显著特点是占 6 0 %的余震估算的应力降出现了小于 0 1MPa以下的极低应力降值 ,整个余震序列的应力降随时间衰减很快 ,这种低应力状态与该次余震序列为弱强度衰减是相一致的 ,表明该次地震的余震序列属于低能量破裂过程更多还原

【Abstract】 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.更多还原