Imaging of Underground Structure Using HAARP
Abstract
Non-invasive imaging of underground structure is important for the detection of hidden tunnels and other hazards, as well as resource exploration, mineral exploration, and environmental contamination problems. We processed and analyzed electromagnetic imaging data sets provided by the Air Force Research Laboratory (AFRL). The main parts of this study included: 1) subsurface imaging using smooth minimum-structure algorithms, 2) adaptation of imaging algorithms for parametric inversions, 3) analysis of the sensitivity and resolution of data to subsurface features and sharp boundaries, and 4) modification of robust processing algorithms for AMT data. Our analysis using synthetic data for simple models indicates the subsurface tunnels can be successfully detected if they are at a depth to diameter ratio of approximately 3:1 or less. Detection of tunnels in actual field conditions is more difficult because of the low signal levels in the AMT frequency range and geologic noise. This was evident in all data sets analyzed under this contract. The HAARP transmitter has the potential to be a valuable exploration tool in that it could generate EM fields that appeared locally as plane waves and could overcome the problems with low AMT signal levels and geologic noise. Our modifications to robust processing algorithms for AMT data and for controlled source data have proven useful for analyzing data with low signal levels and large amounts of noise.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1999
- Accession Number
- ADA398268
Entities
People
- Randall L. Mackie