云南地区与频率有关的P波、S波衰减研究

分析了1999年7月-2003年12月发生在云南地区的由22个地震台站记录的5 668次地震的数字波形资料,从中选出保山、永胜、丽江、鹤庆、易门和禄劝6个地震台用扩展的尾波归一化方法计算P波、S波衰减.这6个台分为3个研究区,保山研究区内Qs-1=0.008 67f-0.86,Qp-1=0.011 55f-0.93;永胜、丽江、鹤庆研究区内Qs-1=0.018 24f-0.94,Qp-1=0.022 88f-0.92;禄劝、易门研究区内Qs-1=0.016 47f-0.91,Qp-1=0.028 26f-0.97.后两个研究区衰减结果比较接近,而保山研究区的P波、S波衰减明显偏低.与全球其它地区采用同样方法得到的P波、S波衰减结果对比表明:永胜、丽江、鹤庆研究区和禄劝、易门研究区的P波、S波衰减与日本关东地区很接近,而远高于韩国东南部的衰减;保山研究区的P波、S波衰减略高于韩国东南部.此外,还与前人得到的云南地区的尾波衰减结果进行了对比分析,发现本文S波衰减值与他们的结果相近.

FREQUENCY-DEPENDENT ATTENUATION OF P AND S WAVES IN YUNNAN REGION

We analyzed digital seismogram data of 5 668 earthquakes that occurred in Yunnan region during July of 1997 to December of 2003, then selected six seismic stations from the 22 ones and calculated their attenuations of P and S waves by using the extended coda-normalization method. We classified six stations into three regions according to their location, that is, Baoshan area, Yongsheng-Lijiang-Heqing (YLH) area and Luquan-Yi-men (LY) area. The values of Q-1s and Q-1p are expressed as Q-1s =0. 00867f-0.86, Q-1p = 0. 01155f-0.93, Q-1s=0. 01824f-0.94, Q-1p =0. 02288f-0.92 and Q-1s =0. 01647f-0.91 , Q-1p = 0. 02826f-0.97 in Baoshan, YLH, LY areas respectively. The attenuation of YHL and LY are closer to each other, however, Baoshan area is apparently lower. Comparing attenuations of the three areas with that in other areas of the world using the same method, it is suggested that the attenuation of P and S wave in YLH area and LY area is close to Kanto of Japan, but much higher than southeast of South Korea. The Q-1s and Q-1p in Baoshan area is slightly higher than southeast of South Korea. Furthermore, the results indicate that our Q-1s in Yunnan area was close to predecessors by analyzing the coda attenuation.