Radio-Echo Sounding: Focusing Effects in Wavy Strata

• Published in: Geophysical Journal International
• Main Author: Harrison, C. H.
• Format: Text
• Language: English
• Published: Oxford University Press 1971
• Subjects: Articles; Antarctic; The Antarctic; Antarc*; Ice Sheet
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/24/4/383; https://doi.org/10.1111/j.1365-246X.1971.tb02185.x

An airborne radio-echo sounding system, employing a wide downward-looking beam, has produced records of the Antarctic ice sheet containing fault-like, near-vertical lines through the strata of partially-reflecting layers within the ice. It is shown that interpretation of these lines as near-vertical faults is in general incorrect, and a more plausible explanation is given developing the geometry of specularly reflected echoes from a stack of continuous undulating strata. An important condition is that the radius of curvature of the reflecting surface must pass from above the observer's path to below: thus the effect of varying observer height is predicted. The effects of refraction at the ice-air interface are a complication which is dealt with later in the paper. Certain fading patterns may also be attributed to wavy layers. It is suggested that misinterpretation in terms of faulting is possible with any echo sounding technique such as sonar, marine seismic, and seismic prospecting, where multiple layering is present.