A field study of azimuthal seismic anisotropy in fractured carbonates at Canyon Lake, central Texas

Mapping Inherited Fractures in the Critical Zone Using Seismic Anisotropy From Circular Surveys

“…The controls on water flow through saprolite are poorly understood, though some studies have found a zone of high hydraulic conductivity near the saprolite/bedrock boundary (e.g., Boisson et al, 2015). Several geophysical methods have been used to study anisotropy due to subsurface fractures, including geophysical borehole logs (Hamm et al, 2007), azimuthal electrical resistivity soundings (Watson & Barker, 1999), self-potential gradient measurements (Wishart et al, 2008), and azimuthal seismic refraction surveys (e.g., Degnan et al, 2001;Hansen & Lane, 1995;Lu et al, 2009). Characterizing subsurface fractures at landscape scales is difficult, however, especially when they are covered by soil and vegetation.…”

“…Characterizing subsurface fractures at landscape scales is difficult, however, especially when they are covered by soil and vegetation. Several geophysical methods have been used to study anisotropy due to subsurface fractures, including geophysical borehole logs (Hamm et al, 2007), azimuthal electrical resistivity soundings (Watson & Barker, 1999), self-potential gradient measurements (Wishart et al, 2008), and azimuthal seismic refraction surveys (e.g., Degnan et al, 2001;Hansen & Lane, 1995;Lu et al, 2009). However, each of these geophysical methods has disadvantages: drilling is expensive and invasive, and the resulting geophysical borehole logs only provide a 1-D representation; electrical soundings and self-potential gradients are largely limited to water-saturated fractures; and azimuthal seismic-refraction profiles are time-consuming, undersampled in azimuth space, and can conflate lateral heterogeneity with anisotropy.…”