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GeoEngineers, Inc. -4 - 111-0920.000 <br />(Roesset, 1991). The dispersion curve is used to create an inversion model that displays <br />the S-Wave velocities at the desired range of depths (Xia, Miller, & Park, 1999). <br />Theoretical dispersion curves are generated via a matrix method (Saito & Kabasawa, <br />1993) and compared against the observed dispersion curve. The model is updated until <br />the observed and theoretical dispersion curves converge. The resulting model is the <br />delivered S-Wave velocity model for the array. <br />4. INSTRUMENTS AND EQUIPMENT <br />4.1 MASW/MAM <br />For this investigation, Global Geophysics used a 24-channel land streamer array of 4.5 Hz <br />geophones at a spacing of 5 feet (distances between geophones were shortened for the <br />soundings inside the storage facility) connected to a Geometrics Geode seismograph. <br />MAM data were collected using ambient seismic waves recorded from the surroundings. <br />Data processing was done with Geometrics SeisImager software package. <br />5. PROCEDURES <br />5.1 Field Deployment <br />MASW 2D S-wave profile <br />A landstreamer with geophone array was laid out along the transects, KEG-40 was used <br />to pound on the ground to generate vibrations. After on screen QA/QC, the array was <br />moved 20 ft to a new location, and used the source to pound on the ground again. <br />MAM Sounding <br />The sounding was located in the parking lot. The survey had an array size of 301 feet <br />Geophone deployment can be seen in Figure 1. <br />5.2 Data Processing <br />5.2.1 Data Processing <br />Data were processed using SeisImager. A dispersion curve is generated from the data <br />and the fundamental mode is picked with the assistance of the software. Uncertain data <br />at high and low frequencies are clipped. The dispersion curve is inverted with the Wave <br />EQ program within SeisImager and an initial model is generated. The model is <br />improved by using a Least Square Method inversion with at least 5 iterations. A series <br />of 1 D soundings along the transects are combined to make 2D profiles. While 1 D deep <br />sounding was processed separately to obtain Vs 100. <br />Global Geophysics <br />