The Effects of Varying Acquisition Parameters and Array Orientations: An MASW Case Study

Abstract

Multichannel analyses of surface wave (MASW) data and electrical resistivity tomography control were acquired at two test sites in central Missouri. Limestone bedrock at both test sites was relatively shallow and dissected in places by solution‐widened joints. The ground surface at both test sites was relatively flat. At each test site, electrical resistivity tomography (ERT) data were acquired along orthogonal traverses that intersected at their centers. The ERT data were acquired in order to determine variable depth using arrays consisting of 60 electrodes spaced at 5 ft intervals. MASW data were also acquired at both sites using a 24‐channel engineering seismograph, a 10 kg sledgehammer and 4.5 Hz geophones. In an effort to test how acquisition parameters affect data characteristics and utility at these sites, MASW data were acquired using variable shot‐receiver offsets (10ft, 20ft, 30ft and 40ft) and variable geophone spacings (2 ft, 5ft and 10 ft). In an effort to test how the source location and array orientation affect data reproducibility, MASW data were acquired along both traverses at each site (using centered arrays) and by discharging the hammer source at both ends of each array. Although the test results are only applicable to the respective test sites, they do demonstrate the extent to which acquisition parameters can affect MASW data quality and the extent to which traverse orientation and source location can affect data reproducibility.