Frequency-Dependent Lg Attenuation in the Indian Platform

Abstract

We use seismograms from regional earthquakes recorded on digital seismographs in peninsular India to determine the frequency-dependent Q of Lg for the Indian platform. We measure Lg attenuation by determining the decay of spectral amplitudes with distance. The available data suggest some spatial variation in attenuation but a much denser ray-path coverage would be required to validate such observations. We, therefore, combine all the measurements of overlapping regions that span both the shield and intervening terranes to obtain an average value of attenuation for the Indian platform: Lg–Q = 665 ± 10 with the frequency exponent n = 0.67 ± 0.03. This average value of Lg attenuation for the Indian platform is similar to the average for other stable regions of the globe.