Passive multichannel analysis of surface waves using 1D and 2D receiver arrays

We use the seismic multichannel analysis of surface waves (MASW) method, which originally used active sources (i.e., controlled by users), to present a new alternative technique for surface-wave analysis of passive data (i.e., seismic sources not controlled by users). Our passive MASW technique uses two types of receiver arrays, 1.D and 2D, for two different purposes. The 2D square array is used for assessing the number and directionality of passive seismic sources to help identify optimal time window(s) when such sources are of sufficient quality and aligned with the ID receiver spread. Then, these time windows are used to selectively extract passive seismic data recorded by the 1D receiver spread for subsequent MASW analysis. In such a manner, this hybrid 1D 2D passive MASW approach can approximate the higher quality advantages of the active MASW method. This technique is successfully applied at a test site in southcentral Kansas taking advantage of train energy as the passive sources monitoring and assessing the potential development of vertically migrating voids that could endanger groundwater and infrastructure. The 1D-2D passive MASW method has proven beneficial for optimizing passive-data dispersion patterns and accurately assessing relative velocities for investigations with reduced labor costs and minimal added processing time and can be considered as a contribution to the surface-wave analysis tools.