【摘要】 利用22个云南区域数字地震台网近震资料,研究了云南地区地震尾波在1²0HZ内6个频段的衰减特征.首先使用单次散射模型计算各台站的尾波衰减系数QC^-1;然后利用随机各向同性散射介质均匀分布的多次散射模型,使用多流逝时间窗分析方法,计算各台站的平均自由程LE和地震反照率B0,得到总衰减系数QT^-1,并从中分离散射衰减系数QS^-1、吸收衰减系数QI^-1.云南地区基本衰减特征是LE主要集中在10³0KM内,在2⁶HZ之间有最大值;B0在1²HZ大致为0.5左右,在其它频段则小于0.5.也即在1²HZ,QI^-1与QS^-1数值相当,其它频段QI-1逐渐大于QS^-1,成为尾波总衰减的主要原因.除1²HZ外,其它频段QC^-1值接近QI^-1.云南地区的Q^-1尤其是QS^-1,在空间上有较大的差异,滇东略微高于滇西北,滇西北高于滇西南地区.与全球其它区域的研究结果比较发现,云南地区QS^-1略低于平均水平,QI^-1略高于平均水平,而QT^-1则处于其它区域结果的中间.更多还原

【Abstract】 The characteristics of seismic coda wave attenuation in Yunnan area in 7 frequency bands from 1 Hz to 20 Hz were estimated by using the local earthquake′s waveform data recorded from 22 Yunnan digital seismic stations. Coda attenuation Q -1 _c of each station was firstly calculated by single scattering method. Then, mean free path L_e and seismic albedo B₀ of each station were calculated, and scattering attenuation Q -1 _s and intrinsic attenuation Q -1 _i were separated from total attenuation Q -1 _t by multiple lapse time window analysis based on the multiple scattering model in uniform random isotropic scattering medium. The attenuating characteristics in Yunnan show that most value of L_e are in 10³0 km, with maxima within 2⁶ Hz; B₀ are about 0.5 at 1² Hz, but less than 0.5 at other frequency bands, which means after 1² Hz, Q -1 _i is greater than Q -1 _s and dominates the attenuation process. Q -1 _c is close to Q -1 _i at other frequency bands except 1² Hz. Results show that Q -1 especially Q -1 _s varies spatially, Q -1 in eastern Yunnan zone is a bit higher than in northwestern Yunnan zone, northwestern Yunnan zone higher than southwestern Yunnan zone. Comparing with other results in global, Q -1 _s in Yunnan is lower than the global average value among these results, Q -1 _i is higher than the global average value, and Q -1 _t lays the middle among these results.更多还原