PNNL

Abstract

Seismic monitoring for underground nuclear explosions answers three questions for all global seismic activity: Where is the seismic event located? What is the event source type (event identification)? If an explosion, what is the yield? Resolution to these questions often involves a seismic analyst processing strong seismic wave propagation with a path largely in the mantle, that is, teleseismic events. This paper develops a mathematical statistics formulation of the teleseismic theory that is the basis for event identification. The four discriminants used to identify teleseismic events are depth from travel time, presence of long-period surface energy (mb versus Ms ), depth from reflective phases, and polarity of first motion. For each discriminant a probability model is formulated under a general null hypothesis of H0 : Explosion Characteristics. The veracity of the hypothesized model is measured with a p-value calculation that is filtered to be approximately Gaussian and ranges between zero and one. A value near zero indicates inconsistency with Explosion Characteristics, and a moderate to large value indicates consistency with Explosion Characteristics (see Stuart et al. (1994)). The hypothesis test formulation ensures that seismic phenomenology is tied to the interpretation of the p-value. Established statistical discrimination methods can be used to formulate a unified decision using all observed discriminants.