Integrated geophysical approach to the detection of buried objects and clandestine tunnels

摘要

Abstract: A planned and integrated geophysical approach, usingall available data, has proven effective in detectingshallow tunnels and buried objects in differentgeological environments. Elements of the integratedapproach included information from intelligence,historical reviews, computer modelling, and multiplegeophysical survey methods. The use of the integratedapproach resulted in a higher rate of success indetecting tunnels and small objects at shallow depths;however, no single survey technique has beenuniversally effective. Several different survey methodswere used to determine specific characteristics of apotential target. Magnetic sensors detectedferromagnetic materials used in tunnel construction.Analyses of the magnetic anomaly characteristics andthe surface patterns of the anomalies indicated thedepth and path of the tunnel. Tunnels were alsodetected by intrinsic parameters of observedelectromagnetic anomalies and the surface patterns ofinstrument responses. Both methods have successfullydifferentiated materials used in tunnel constructionand operational support systems from surface featuressuch as utility or sewer lines. Cross-borehole radarwas used to confirm the existence of a deep tunnelthrough crystalline rock in the southern part of theDemilitarized Zone in the Republic of Korea. Additionalindications of tunnels were obtained from analyses ofmigrated seismic compression waves (P- waves) collectedby a vertical stack, common-midpoint method. Ground-penetrating radar (GPR) and magnetic and EM sensorswere effective in detecting shallow-depth cachesconstructed of various materials.!3