Measurements and interpretation of normal mode attenuation

Abstract

summary. Measurements of Q for modes of free oscillation provide the most accurate information about the anelastic properties of the whole Earth in the period range from 100 to 3000 s. We have obtained more than 230 Q measurements, by using two different techniques. Individual LaCoste—Romberg gravimeter recordings of three large earthquakes were used to observe the time rate of decay of spectral peaks corresponding to different modes. This method provided measurements of Q for 37 different modes. By stacking 211 WWSSN recordings of two deep earthquakes, we were able to measure Q for 197 modes, including many overtones which cannot be analysed using the spectra of individual recordings. Copyright © 1978, Wiley Blackwell. All rights reserved