Operational and functional capabilities of the SNDA as a system for SASA data analysis are illustrated below by its application to the problem of detection and parameter estimation of a so called "hidden explosion" seismic signal. The possible scenario of avoiding a Comprehensive Test Ban Treaty is to perform secret nuclear test by triggering a nuclear device with a seismic signal from a rather strong earthquake. In this case the explosion wave phases are obscured by coda waves of the earthquake. Latter typically have an intensity significantly stronger than seismic noise at observational sites of the monitoring network. Nevertheless, registering of a noise field by a SASA and processing SASA recordings with the help of special statistically optimal algorithms provides a chance of reliable CTBT monitoring even in the case of implementing of the avoiding scenario described.
Figures (shown below) illustrates results of application of the SNDA advanced processing methods to the "hidden explosion" problem. In this study we used multichannel seismograms from underground nuclear test at Novaya Zemlya site (24 Oct. 1990) and earthquake in Hindu Kush (25 Oct. 1990) registered by NORESS SASA. Simulation of NORESS recordings containing a "hidden explosion" signal obscured by an earthquake coda and seismogram processing for explosion signal detection and parameter estimation were made with the help of a special SNDA script, comprising a variety of the SNDA stack commands and SA-procedures.