Q of the Indian Shield

by S. K. Singh, D. García, J. F. Pacheco, R. Valenzuela, B. K. Bansal, and R. S. Dattatrayam

Abstract

We analyze spectral attenuation of Lg waves to determine Q of the Indian shield. The dataset consists of four earthquakes recorded in the distance range of 240–2400 km. The new estimate, Q(f) = 800f ^0.42 (0.1 Hz ≤ f ≤ 20 Hz), is based on a larger dataset than a previous estimate, Q(f) = 508f ^0.48 (1 Hz ≤ f ≤ 20 Hz). The new Q(f) of the Indian shield is comparable to the Q in regions of eastern North America where its value is relatively high, for example, the Adirondack Mountains. It is also in agreement with previously reported Lg coda Q at f = 1 Hz for the Indian subcontinent. The revised Q(f) has important implications for the estimation of ground motions in the Indian shield region using the stochastic method since the recorded data, presently, come mostly from large distances.

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