Definition of exclusion zones using seismic data

In verifying compliance with tile Comprehensive Nuclear-Test-Ban Treaty (CT BT), there is a motivation to be effective, efficient and economical and to prevent abuse of the right to conduct an Onsite Inspection (OSI! in the te rritory of a challenged State Party. In particular, it is in the interest o f a State Party to avoid irrelevant search in specific areas. In this study we propose several techniques to determine 'exslusion zones', which are de fined as areas where an event could not have possibly occurred. All techniq ues are based on simple ideas of arrival time differences between seismic s tations and thus are less prone to modeling errors compared to standard eve nt location methods. The techniques proposed are: angular sector exclusion based on a tripartite micro array, half-space exclusion based on a station pair, and closed area exclusion based on circumferential networks.