oa Removing topography influence in VLM-EM data by linear filtering

When surveying upon a level homogenous halfspace or over borizontally layered lithologies no anomalies are seen in the conventional VLF-EM method. But in situations where the topography represents a surface with varying relief even upon a homogenous halfspace the terrain itself will generate VLF-EM anomalies which can be misinterpreted as originating from subsurface conductors.