f Data processing techniques designed to improve MT data quality

There has been a number of examples of MT soundings intended for investigating the crustal structure (e.g. Hermance and Garland, 1968; Word et al., 1971; Vozoff, 1972). In recent years, developments in the MT method have enabled us to derive a fairly reliable crustal resistivity structure through remarkable improvements in measuring instruments (e.g. Petiau and Dupis, 1980; Fischer, 1982; Morrison et al., 1984), data processing (Word et al., 1970; Kao and Rankin, 1977; Wight and Bostick, 1980) and interpretation (e.g. Rodi, 1976; Bostick, 1977; Oldenburg, 1979).