Seismic Yield Estimation Using Teleseismic P- and PKP-Waves Recorded at the GRF-(Grafenberg) Array

Abstract

Summary In this paper the ‘transportability’ of magnitude-yield relations for nuclear explosions at the Nevada Test Site (NTS), USA is investigated. This test of applicability is done by comparing the yield estimates obtained in this study for the NTS and other test sites at eastern Kazakhstan, Novaya Zemlya and Mururoa (French Polynesia) to selected yield estimates of more large-scale investigations using different and more comprehensive data sets. It is shown that the transportability of magnitude-yield relations becomes possible if the differences in the absorption of seismic body waves in the upper mantle beneath the different test sites are correctly accounted for. to estimate the yields of explosions from the four test sites, a single magnitude-yield relation has been used and a uniform methodology has been applied for the determination of source-region corrections for upper mantle attenuation. A linear relation between the Grafenberg station-magnitude mb(GRF) and the network magnitude of the ISC is established, which can be used to predict the network mb from a measurement of mb(GRF). Recordings from PKP-waves from French nuclear explosions in Mururoa can, through the appropriate determination of a core-phase magnitude mb(GRF), be used analogously for yield estimation: However, because of the possible network-bias problem for mb measurements of Mururoa events and because of the less well known absorption correction the results for that test site must be considered less substantiated. Using the derived magnitude-yield relations the smallest observed magnitudes can be converted into yield values. the detection threshold of the GRF-array for the single station A1 lies in the kt-range for the eastern Kazakhstan and Novaya Zemlya test sites and in the 10-kt range for the Nevada Test Site. the detection threshold of the GRF-array beam for the Mururoa test site lies in the kt-range.