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...rrelation because measurements of thescomponents of true groundforce not having been accurately obtained.sThe crosscorrelation operation can be expressed bysxcc(t) = r(t) * s(t) s(t) = r(t) * k(t) (=-=Yilmaz, 2001-=-)swhere xcc(t) is the cross-correlation, r(t) is the geological reflectivity, s(t) is thessweep,s* is the convolution operator, is the cross-correlation operator, k(t) is thesKlauder wavelet, and al...

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... an effort to improve frequencies ands9ssignal-to-noise ratios, optimized sensors, placement and recording were tested.sGroundforce can be calculated using a weighted sum formula:sF = mb xb + mr xr, (=-=Sallas, 1984-=-)swhere F is groundforce, mb is the mass of the baseplate (370 lbs), xb is the baseplatesacceleration, mr is the mass of the reaction mass (311 lbs), and xr is the reaction masssacceleration.sCross-co...

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...llington Aquifer.sGroundwater within thesWellington Aquifer moves in all directions from the potentiometric high east ofsHutchinson, KS and moves vertically due to changes in density along the fronts(=-=Gogel, 1981-=-).sPermian units including the Hutchinson Salt Member (up to 100 m thick nearsHutchinson) unconformably underlie Tertiary/Quaternary Equus Beds (Figure 3) atsthe survey site.sThe salt dips westward at...

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...ct on thescross-correlation results (Brittle, 2001).sNon-rigid motion (structural flexing) of the baseplate can cause errors in usingsthe weighted sum formula (Sallas, 1984) to calculate groundforce (=-=Schrodt, 1987-=-).sEach baseplate accelerometer measures the acceleration of the baseplate at one singleslocation and uses that to estimate acceleration across the entire plate.sIt has beensshown that at high frequen...

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..., synthetic sweeps were created to match the vibrator’s drivessignal for each survey.sA sweep is an oscillating signal with time-variant amplitudesand a frequency that varies monotonically with time (=-=Goupillaud, 1976-=-).sThe sweepsswere cross-correlated with the recorded vibroseis signal traces to produce asreflectivity series (Figures 19 and 20 are shot gathers from equivalent surfaceslocations).sCross-correlation...

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...ed in the deposition of sand,sgravel, and porous rock in the western half of the state.sThe Quaternary began 1.6smillion years ago with episodes of erosion.sDeposition consisted of sands and gravelss(=-=Merriam, 1963-=-).sAt the Reno County study area, a significant amount of erosion hassoccurred as evidence by the complete lack of Mesozoic and Tertiary materials.s10sGroundwater access to Permian units improved foll...

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...tempts to equalize or flatten all amplitudes in the frequencysdomain.sTherefore, all the frequencies in the sweep are considered to have identicalsamplitudes after deconvolution is applied correctly (=-=Bickel, 1982-=-).sThis effectivelysboosts the high frequency portion of the post correlated data.sVibroseis whitening issa method commonly applied to vibroseis data prior to cross-correlation with thessynthetic swee...

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...mmon-midpoint (CMP)sapproach consistent with 2-D high-resolution vibroseis data (Figure 18) (Lambrecht,s2006; Steeples and Miller, 1994; Miller et al., 2002; Miller et al., 2008; Miller et al.,s2006; =-=Miller et al., 1993-=-).sProcessing software (WinSeis) developed at the KGS wassused for all processing.sProcessing steps were kept as simple as possible in an effortsto accurately compare the 2001 and 2008 data sets.sData...

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...an result in sudden or gradual surface collapse.sWithsanthropogenic dissolution, voids will generally migrate more vertically as comparedsto horizontal migration seen in natural dissolution features (=-=Walters, 1978-=-).sSurface expression and associated problem at US 50 and Victory RoadsGPS data collected by KDOT from October 1998 to October 2000 show asdrop in the elevation of the centerline of US 50 of 0.12 m (F...

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...dent, frequency errors occur with anystime spectral variations (Brittle, 2001).sSweep deconvolution involves the same convolutional model as crosscorrelation but is performed in the frequency domain (=-=Ghose, 2002-=-).sConvolution insthe frequency domain is multiplication; the equation can be written as:sX(ƒ) = R(ƒ)S(ƒ)swhere X(ƒ) is the recorded trace, R(ƒ) is the geological reflectivity, and S(ƒ) is thessweep. ...

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... bowl-like shape surface geometry.sSeismic surveys in Reno Countystargeting individual sinkholes have generally focused on the upper 250 m to imagesany dissolution feature within the Hutchinson Salt (=-=Miller, 2002-=-; Miller, 1993;sNissen, 2002).sIn its thickest locations, the Hutchinson Salt can be 145 m thick withsa basal contact 240 m below ground surface.sPast surveys have successfullysproduced good signal qu...

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...sPrevious experiments with low noise accelerometer and tuned placementsswere expanded to a full field trial on this survey as part of continued attempts to boostsresolution and signal-to-noise ratio (=-=Rademacker, 2006-=-).sTwo types ofsaccelerometers were used for recording (one pair on the mass and one pair on thesbaseplate) during the 2008 acquisition.sThe Dytran 3184 model accelerometer with assensitivity level of...

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... gathers in reflectionsslater than 200 ms (between traces 100 and 117 at 210 ms) (Figure 34).sTime delayss(pull downs) and geometric distortions are expected when imaging beneathssubsidence features (=-=Anderson et al., 1995-=-) (Figure 37).sTime delays are caused bysdecreases in material velocities caused by changes in compaction structures andsmaterial bulk properties within the synform (Figure 37 (b)).sDiffractions ands5...

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...echt, 2006; Miller et al., 2006).sThe success of time-lapse surveyssdepends on repeatability (Bertrand, 2008).sRepeatability is affected by sourcessignature (Saunders, 2004), amplitude and frequency (=-=Bisshop, 1994-=-), processingstechniques (Lecref, 2004), and near-surface conditions (Yun, 2007).sTechniques have been used in the oil and gas industry to equalize time-lapsesseismic data.sOne such approach involves ...

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... to produce asreflectivity series (Figures 19 and 20 are shot gathers from equivalent surfaceslocations).sCross-correlation using a synthetic sweep to represent the vibrator’s opensloop drive signal (=-=Cunningham, 1979-=-) is a common process used in processing forssingle source vibroseis data (Yilmaz, 2001).s29sFigure 18. Common 2-D high-resolution near-surface seismic-reflectionsprocessing flow (modified from Lambre...

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...ng issa method commonly applied to vibroseis data prior to cross-correlation with thessynthetic sweep to enhance target signals.sThe upper portion of the usable bandwidthsoften contains weak signals (=-=Doll and Coruh, 1995-=-).sDeconvolution eliminates thesneed for vibroseis whitening by enhancing the higher frequency portion of thessignals.sGroundforce is a measure of the energy input into the ground in vibroseissexplora...

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...for bothssurveys (+/- 1 m variation).sStatic problems are common in reflection data collectedsin areas where near-surface layers are disturbed by subsidence, resulting in lateralsvelocity variations (=-=Frei, 1995-=-).sEvent arrival times can be altered severalsmilliseconds at this site by changes in velocities and distorted rock layers in the uppers30 m (Miller, 2002).sVibroseis whitening was applied to the unco...

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...on data is highsambient noise and low signal levels within the high frequency portion of the sweeps28s(Doll and Coruh, 1995).sVibroseis whitening increases the resolution of near-surfacesreflections (=-=Klemperer, 1987-=-).sSince telemetried groundforce was recorded as channel 1 during acquisition,sthe pilot for these data was created during processing to posses the appropriatesfrequency range and tapers for the diffe...

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...in central Kansas. Timelapse seismic reflection methods are routinely used for reservoir monitoring (Wang,s1997).sAnthropogenic salt dissolution features have been studied using time-lapse insKansas (=-=Lambrecht, 2006-=-; Miller et al., 2006).sThe success of time-lapse surveyssdepends on repeatability (Bertrand, 2008).sRepeatability is affected by sourcessignature (Saunders, 2004), amplitude and frequency (Bisshop, 1...

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.... Timelapse seismic reflection methods are routinely used for reservoir monitoring (Wang,s1997).sAnthropogenic salt dissolution features have been studied using time-lapse insKansas (Lambrecht, 2006; =-=Miller et al., 2006-=-).sThe success of time-lapse surveyssdepends on repeatability (Bertrand, 2008).sRepeatability is affected by sourcessignature (Saunders, 2004), amplitude and frequency (Bisshop, 1994), processingstech...

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...mic Data ProcessingsVictory Road SinkholesBoth seismic data sets were processed using a common-midpoint (CMP)sapproach consistent with 2-D high-resolution vibroseis data (Figure 18) (Lambrecht,s2006; =-=Steeples and Miller, 1994-=-; Miller et al., 2002; Miller et al., 2008; Miller et al.,s2006; Miller et al., 1993).sProcessing software (WinSeis) developed at the KGS wassused for all processing.sProcessing steps were kept as sim...

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... Hutchinson Salt Member and the location ofsthe study site within Reno County, Kansas (Miller, 2002).sFigure 2. 2001 survey in the north road ditch, 2008 surveysin the south road ditch (modified from =-=Williamson, 2008-=-).s6sSeismic study along Highway 50sThe KGS began acquiring seismic data in 2003 to delineate rock layers withinsand above the Hutchinson Salt Member and attempt to appraise the overall stability ofst...