Detection Of Underground Voids With Surface Waves

The conventional approach to the detection of underground voids by the Spectral Analysis of<br>Surface Waves (SASW) method is through analysis of the phase difference between two<br>transducers. This approach requires lengthy field testing and complex data manipulation,<br>including filtering and unwrapping of the phase function. In the frequency domain two properties<br>are measured for each frequency, its amplitude and wrapped phase value. This study proposes a<br>method for the detection of underground voids by analyzing the measured power spectral<br>density, a function related to the amplitude of the frequency. The proposed method does not<br>require complex data manipulation since the power spectral density is directly measured and<br>testing can be completed with an oscilliscope, decreasing the time required to conduct a seismic<br>survey.