Abstract

Rg signals measured between 1 and 5 Hz at local and near‐regional distances provide a viable method for estimating the yields of atmospheric and underground explosions. However, tested methods have been restricted to single or slowly changing source and receiver geologies, because propagation across abruptly changing geological boundaries can cause large reflections of the propagating Rg signals resulting in unacceptably large errors in yield estimates. In this article, we demonstrate how to correct for transmission and reflection across boundaries if estimates of the layered velocity, density, and attenuation structure in the different geological media are known. The methodology developed is tested using the alluvium and limestone structures analyzed in detail for the Humble Redwood (HR) III (2012) explosions conducted near Albuquerque, New Mexico. We validate the technique against the HRI (2007) and HRII (2009) atmospheric and underground explosions conducted in the same geologies as HRIII, with propagation paths crossing both alluvium and limestone. We compare synthetic estimates of yields of the HRI and HRII explosions based on earth structure to the known yield of 540 kg for these events. With no alluvium–limestone transmission correction, the estimated yield for the atmospheric explosion is 31 kg, and underground is 53 kg, which are both grossly inaccurate. The estimated yield after applying the transmission correction for the atmospheric explosion is 590 kg, and for the underground explosion is 617 kg, giving respective yield errors of 9% and 14%.

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