Share Email Print

Proceedings Paper

Tunnel detection using the radio imaging method at the Otay Mesa site
Author(s): Kenneth D. Mahrer; William A. Mondt
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

We demonstrated that radio imaging method (RIM) surface-to- surface, borehole-to-surface, and borehole-to-borehole sensing technologies at the Otay Mesa test site east of San Diego, CA could detect and delineate a horizontal 4 X 6-foot (cross- section) tunnel buried at a depth of approximately 45 feet. Utilizing monochromatic, continuous wave electromagnetic signals from a magnetic dipole source operating in the range between 22 kHz and 15 MHz, we confirmed the effectiveness of two general approaches: (1) mapping the electrical conductivity contrast between the country rock (sandstone) and the tunnel (i.e. the void and surrounding desiccation fractures) and (2) locating a cable (i.e. conductor) within and running the length of the tunnel from its induced, secondary radiation. Surface-to-surface RIM, utilizing a gradiometer receiver, mapped the 2D plan view location of the tunnel. Borehole-to-surface delineated both the depth and plan view location of the tunnel. Borehole-to-borehole RIM delineated the depth of the tunnel.

Paper Details

Date Published: 22 July 1994
PDF: 10 pages
Proc. SPIE 2217, Aerial Surveillance Sensing Including Obscured and Underground Object Detection, (22 July 1994); doi: 10.1117/12.179932
Show Author Affiliations
Kenneth D. Mahrer, RIMtech, Inc. (United States)
William A. Mondt, RIMtech, Inc. (United States)

Published in SPIE Proceedings Vol. 2217:
Aerial Surveillance Sensing Including Obscured and Underground Object Detection
Ivan Cindrich; Nancy DelGrande; Sankaran Gowrinathan; Peter B. Johnson; James F. Shanley, Editor(s)

© SPIE. Terms of Use
Back to Top