Abstract: A method and apparatus for detecting underground structures using muon tomography in conjunction with a horizontal borehole. The system involves drilling or tunneling a horizontal borehole beneath the expected subsurface substructure depth, deploying multiple muon detector units within the borehole, equipment for moving the detector sonde along the borehole, recording data, and analyzing the detected muon flux to identify anomalies indicative of tunnels. The muon detectors, configured as tubular bundles of scintillators and drift tubes, detect muons with energies ranging from 10 GeV to 1 TeV and record the path of the muons. The system ensures borehole integrity and precise drilling alignment, providing a reliable means for subsurface structure detection.

Abstract: A method and system for detecting a subsurface tunnel includes propelling an instrumented pipeline pig through a horizontal detection conduit, acquiring and analyzing magnetometer measurements and VLF EM resistivity measurements to detect distortions and/or anomalies in the Earth's magnetic field and/or VLF electromagnetic field, respectively, and correlating the data with position data of the pipeline pig to compute a parameter of a tunnel such as, for example, location, size and depth.