9614136 Zhdanov Electromagnetic (EM) probing of the earth is one of the major tools for surveying underground structures and the technique is used to map the earth from the crust to the mantle. Applications include geological mapping, mineral and oil prospecting, tectonic and earthquake studies, and environmental assessment and monitoring. One of the most difficult problems of EM geophysical methods is the interpretation of EM data in areas with 3-D geo-electrical structures because of limitations of 3D forward modeling codes and ill-posedness of inversion procedures. Currently available EM techniques can handle only simple models and require supercomputer processing. The PI proposes to develop fast and stable 3-D geo-EM inversion methods that can be applied to real geophysical data using conventional PCs or Workstations using new methods based on quasi-linear approximations of the existing integral equation algorithms. ***
