Terrain Considerations and Data Base Development for the Design and Testing of Devices to Detect Intruder-Induced Ground Motion

Abstract : This study attempted to develop a readily accessible body of information that defines the ranges of intruder signal characteristics within which seismic sensors for intruder detection, classification, and location must operate. The principal product of the study was a data base of seismic signatures (recorded on magnetic tape) that contains representation of the range of target types, travel modes, terrains, and background noise sources that can realistically be expected to occur for base and installation environments and in operational scenarios. Both an experimental and a theoretical approach were taken. The first approach consisted of collecting and analyzing the signatures of intruders and background noise sources in a wide range of terrain conditions (as determined from bulk properties describing the compression and shear strength of the media, moisture, density, etc.). The theoretical approach consisted of applying mathematical models of the seismic signature generation and propagation phenomena so as to extend the data base of seismic signatures to include terrain conditions not represented in the data collection portion of the work. The mathematical models were also used to evaluate site documentation procedures and to estimate the frequency of occurrence of groups of terrains for which similar signature characteristics can be expected to occur.