Effects of Source RDP Models and Near-source Propagation: Implication for Seismic Yield Estimation

• Published in: Pure and Applied Geophysics
• Main Authors: Saikia, Chandan K., Helmberger, D. V., Stead, R. J., Woods, B. B.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 2001
• Subjects: Haskell; Novaya Zemlya
• Online Access: https://authors.library.caltech.edu/98340/; https://resolver.caltech.edu/CaltechAUTHORS:20190829-131532824

It has proven difficult to uniquely untangle the source and propagation effects on the observed seismic data from underground nuclear explosions, even when large quantities of near-source, broadband data are available for analysis. This leads to uncertainties in our ability to quantify the nuclear seismic source function and, consequently the accuracy of seismic yield estimates for underground explosions. Extensive deterministic modeling analyses of the seismic data recorded from underground explosions at a variety of test sites have been conducted over the years and the results of these studies suggest that variations in the seismic source characteristics between test sites may be contributing to the observed differences in the magnitude/yield relations applicable at those sites. This contributes to our uncertainty in the determination of seismic yield estimates for explosions at previously uncalibrated test sites. In this paper we review issues involving the relationship of Nevada Test Site (NTS) source scaling laws to those at other sites. The Joint Verification Experiment (JVE) indicates that a magnitude (m_b) bias (δm_b ) exists between the Semipalatinsk test site (STS) in the former Soviet Union (FSU) and the Nevada test site (NTS) in the United States. Generally this δm b is attributed to differential attenuation in the upper-mantle beneath the two test sites. This assumption results in rather large estimates of yield for large m_b tunnel shots at Novaya Zemlya. A re-examination of the US testing experiments suggests that this δm_b bias can partly be explained by anomalous NTS (Pahute) source characteristics. This interpretation is based on the modeling of US events at a number of test sites. Using a modified Haskell source description, we investigated the influence of the source Reduced Displacement Potential (RDP) parameters