Electromagnetic Impedance System for Mapping Shallow Subsurface
Hung-Wen Tseng, Ki Ha Lee and Alex Becker
Lawrence Berkeley National Laboratory, USA.
Contacts: khlee@lbl.gov (Ki Ha Lee)
Abstract
Non-invasive, high-resolution imaging of the shallow subsurface is one of the key elements for successfully delineating buried waste, detecting unexploded ordinance, verifying and monitoring of containment structures, and other environmental applications. Electromagnetic (EM) measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data can be mapped into the space of the subsurface parameters. We have been developing a non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using the EM impedance approach (Frangos, 2001; Lee and Becker, 2001). Electric and magnetic sensors are being tested in a known area against theoretical predictions to ensure that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques. Additional efforts are being made in modifying and further developing existing sensors and transmitters for improved imaging capability.
raeg2003@tansa.kumst.kyoto-u.ac.jp
Last modified: Wed Dec 25 16:49:57 2002