Scattering of Surface Waves due to Shallow Heterogeneities
Abstract
Shallow buried heterogeneities act as diffractors to an incoming surface wave. Experimental and numerical analyses are conducted to analyze the problem and to propose a methodology for mapping shallowly embedded objects. A layered system having a high impedance contrast at the base containing shallowly buried drums is tested experimentally. Stacked maps of frequency, velocity and lateral position show the presence of the drums. A hypothesis is posed that the most significant impact of the shallow obstacle on the incident wavefield is diffraction ofRayleigh wave energy. Synthetic seismograms generated through numerical modeling support the hypothesis. The interpretation of the data is complicated by factors such as acquisition footprint and frequency content. These factors remain to be investigated.