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Multi-fold TDEM Experiment Design for Near Surface Conductivity Mapping

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dc.contributor.authorKazlauskas, Eric Michaelen
dc.contributor.committeechairWeiss, Chester J.en
dc.contributor.committeememberSpotila, James A.en
dc.contributor.committeememberSchreiber, Madeline E.en
dc.contributor.departmentGeosciencesen
dc.date.accessioned2014-03-14T20:43:23Zen
dc.date.adate2010-09-07en
dc.date.available2014-03-14T20:43:23Zen
dc.date.issued2010-08-02en
dc.date.rdate2010-09-07en
dc.date.sdate2010-08-13en
dc.description.abstractMulti-fold Time Domain Electromagnetics (TDEM) is a novel experimental approach that couples elements of traditional land-based TDEM survey designs to obtain a robust data set. This design inherently accommodates a broad range of possible Earth models through a rich combination of analysis opportunities making it ideally suited for reconnaissance. Kentland Farms, VA was chosen as the test site, for its ease of access and interesting geologic features such as river terraces and karstic landscape. Three independent methods of analyzing the 3-component data set each provided unique insights into the subsurface electrical structure through a complementary interpretation. Synthesis of log-normalized ∂tB<sub>z</sub> pseudo-sections provided a first-order analysis of the lateral and vertical heterogeneities of the profile. A Zero-Crossing Moveout (ZCMO) analysis used a brute-force grid-search inversion to estimate the two-layer Earth model that best-fit the observed moveout times for a range of interface depths. By using the ZCMO result as an initial model, regularized 1D Occam inversions determined a 3-layer electrical structure consisting of a 3.5 m – 5 m thick resistive upper layer, over an 12.5 m – 15 m thick conductive layer, overlying a resistive half-space. From correlation of the inverse solutions with ZCMO derived conductivity models and prior resistivity information, the depth to the limestone bedrock was approximated to be 16 – 20 m. The delineation of the bedrock depth provided additional support for the fill-cut terrace formation model (Ward et al., 2005), as well as possible evidence of groundwater drainage on the 40 m terrace at Kentland Farm.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-08132010-142957en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08132010-142957/en
dc.identifier.urihttp://hdl.handle.net/10919/34513en
dc.publisherVirginia Techen
dc.relation.haspartKazlauskas_EM_T_2010.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectZero-crossing moveouten
dc.subject1D inversionen
dc.subjectdepth to bedrocken
dc.subjectKentland Farms geologyen
dc.subjectexperiment designen
dc.subjecttime domain electromagneticsen
dc.subjectconductivity mappingen
dc.titleMulti-fold TDEM Experiment Design for Near Surface Conductivity Mappingen
dc.typeThesisen
thesis.degree.disciplineGeosciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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