{"thcode":2,"term":{"code":2087,"name":"electrical resistivity imaging","parent":326,"scope":"Land-based resistivity survey where current is applied to the ground using an array of electrodes and apparent resistivity of the subsurface is measured, giving estimates of the spatial variability of resistivity (for example, variations in pore water salinity)."},"uf":[{"name":"ERT surveying","usewith":false},{"name":"electrical resistivity tomography","usewith":false}],"bt":[{"code":326,"name":"electromagnetic surveying","parent":375,"scope":"Method of determining the shape and constituency of near-surface earth structures by variations of responses of the materials to electrical and magnetic fields. Use for ground-based methods of imaging."},{"code":375,"name":"field inventory and monitoring","parent":376,"scope":"Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis.  In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis."},{"code":376,"name":"field methods","parent":734,"scope":"Research procedures and instrumental means to measure, collect data and samples, and observe in the natural areas where the materials, phenomena, structures, or species being studied occur."},{"code":734,"name":"methods","parent":1,"scope":"Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[],"rt":[]}