Anelasticity of the Crust and Upper Mantle of South America From the Inversion of Observed Surface Wave Attenuation |
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| Authors: | Edward O Osagie |
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| Institution: | Department of Physics, University of Benin, Benin City, Nigeria |
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| Abstract: | Fundamental-mode Rayleigh and Love waves generated by several earthquakes situated along great-circle paths between pairs of seismograph stations have been analysed to obtain coefficients of attenuation, group velocities, phase velocities, and specific quality factors in the period range 18–80s in two regions of the South American continent. One set of paths crosses the shield region which lies on the eastern coast and another set traverses the mountainous region inland. the average attenuation coefficient values are clearly higher in the tectonically active western region throughout the entire period range than in the eastern or shield region.
Inversion of the attenuation data yielded shear wave internal friction ( Q -1β) models as a function of depth in the crust and upper mantle in both regions. A low- Q zone below the lithosphere is prominent in both regions. the results show that substantial variations of Q β occur in the two regions of South America. the Qβ values were found to be inversely related to the heat flow values or to the temperature. |
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| Keywords: | anelasticity attenuation inversion surface waves |
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