地震学报（英文版）1999，Vol.12Issue(1)：1-10,10.
High frequency fall-off of source spectra using Q-free spectra estimation
High frequency fall-off of source spectra using Q-free spectra estimation
摘要
Abstract
A broadband seismogram may be represented by a convolution of source time function, the propagation operator and the scattering/attenuation operator. As the propagation operator is frequency-independent, and the scattering/attenuation effect may be described by a Q-factor depending on frequency via Q-1=Q-11+(Q2ω)-1, considering a combination of the displacement spectra, the source spectra may directly be estimated, in which the contribution of the Q-value may be eliminated automatically. Using this algorithm, the near-source broadband seismograms of five aftershocks of the 1988 Lancang-Gengma, Yunnan Province, China earthquake were processed. The results for the ML=3.0 and ML=3.5 aftershocks show that for the same earthquake, similar high-frequency fall-off may be obtained from different recording stations. The result for the MS=6.7 aftershock shows that consistent source parameters may be gotten from different seismic stations. The parameters estimated also agree with the results obtained by empirical Green's function approach. The high-frequency spectra of the aftershocks exhibit a typical f-γ fall-off. For the ML=3.0 aftershock,γ≈3 ; for the MS=6.7 and ML=4.0 aftershocks,γ≈2; and for the ML=3.5 and ML=3.0 aftershocks, γ≈2.5. The corner frequency of the MS=6.7 aftershock indicates that it has a small source dimension, implying that it may come from the rupture of a small but strong barrier.关键词
source spectra Q-value Lancang-Gengma earthquakeKey words
source spectra Q-value Lancang-Gengma earthquake分类
天文与地球科学引用本文复制引用
..High frequency fall-off of source spectra using Q-free spectra estimation[J].地震学报（英文版）,1999,12(1):1-10,10.基金项目
This work is supported by the Joint Seismological Sciences Foundation (95-07-411). Also partly supported by NSFDYS49725410. Contribution No. 99FC2003, Institute of Geophysics, China Seismological Bureau, China. （95-07-411）
