| Regional features of coda attenuation of aftershocks of Wuding, Yunnan earthquake in near field |
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| 作者姓名： | 秦嘉政 李白基 钱晓东 苏有锦 蔡静观 付虹 |
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| 作者单位： | QIN Jia-zheng ? LI Bai-ji? QIAN Xiao-dong ? SU You-jin? CAI Jing-guan ?FU Hong Seismological Bureau of Yunnan Province，Kunming 650041，China |
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| 基金项目： | National Key Fundamental Research Plan (Mechanism and Prediction of Continental Strong Earthquake( - Moving Test Field in Wester |
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| 摘 要： | IntroductionSeismic wave is an important information source to analyze and study seismic source and internal structure of the earth. Studies of wave on different frequency ranges can provide many features of seismic source and internal structure of the earth. In recent years in quantitative study of seismic wave seismologists at home and abroad have developed a wide study field on the coda. Especially seismologists have done a lot of work in coda geneses, mechanism and its attenuation to explo…
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| 收稿时间： | 13 March 2000 |
| 修稿时间： | 27 October 2000 |
Regional features of coda attenuation of aftershocks of Wuding, Yunnan earthquake in near field |
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| QIN Jia-zheng,LI Bai-ji,QIAN Xiao-dong,SU You-jin,CAI Jing-guan,FU Hong.Regional features of coda attenuation of aftershocks of Wuding, Yunnan earthquake in near field[J].Acta Seismologica Sinica(English Edition),2001,14(1):91-100. |
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| Authors: | QIN Jia-zheng LI Bai-ji QIAN Xiao-dong SU You-jin CAI Jing-guan FU Hong |
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| Institution: | Seismological Bureau of Yunnan Province, |
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| Abstract: | According to dispersion theory of coda of local events, using near-field data of aftershocks recorded by two mobile digital stations at the Tianxin and Yunlong after the Wuding, Yunnan MS=6.5 main-shock and sampling at different central frequencies (1.5~20 Hz), spatial distribution features of coda attenuation ratio ( ( f ) are studied. The results show that there exists obvious non-uniformity of coda attenuation ratio ( ( f ) given by the two stations in small region. When f <6.0 Hz the coda attenuation ratio ( ( f ) observed on both sides of earthquake-generating fault are basically identical. Yunlong station is located on east side and Tianxin station on west side. The corresponding Qc( f ) is in the range of 66~120. However, in the range of high frequency ( f (6.0 Hz) the coda in near field going through major fault encounters a strong absorption from the fracture zone. The ( ( f ) going through the fault observed at Yunlong station is 30% lower than that in Tianxin station in which the seismic waves do not go through the fault. The reason for the difference in space distribution of coda attenuation is discussed. The results also show that factor A0( f ) of wave source is not only related to the source strength, but also to frequency f. The mean free path L of S wave obtained using 1.5~20 Hz is respectively 30 km on east side of the fault and 40 km on west side, from which it is verified that there is a stronger dispersion body when seismic waves go through the fracture zone. |
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| Keywords: | coda attenuation in near field space distribution of Qc( f ) local inhomogeneity Wuding earthquake |
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