Acoustic Reflection Coefficient; A Forward and Inverse Scattering Model for Ice and Bed Topography
Open Access
- Author:
- Kudekar, Aneesh Rajendra
- Graduate Program:
- Acoustics
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 10, 2014
- Committee Members:
- Sridhar Anandakrishnan, Thesis Advisor/Co-Advisor
Victor Ward Sparrow, Thesis Advisor/Co-Advisor
Daniel Allen Russell, Thesis Advisor/Co-Advisor - Keywords:
- acoustic scattering
reflection coefficient - Abstract:
- Scientific study of the bed rock structure, glaciers and ice layers on the frozen continent of Antarctica and countries like Greenland has been going around for more than a century by now. Scientists are interested in the evidences of Earth's geographic evolution captured by the natural preserving mechanisms around the polar areas. Geophysicists have been analyzing seismic reflection data for commercial and academic interests. Reflection seismology and seismic surveying techniques have been developed for getting a better understanding about our planet. Almost all commercial hydrocarbon and oil exploration use some form of seismic surveying to locate reserves and characterize them. Natural surfaces are never perfectly smooth. Seismic reflection from rough sub-glacial bottom boundaries is affected and influenced by scattering. This phenomenon makes the reflected energy deviate in different directions apart from the specular reflection. This effect results in erroneous conclusions about the surveyed geological area. I have attempted a model to investigate the surface properties based on observed reflection coefficient for ice-over-bed-rock topology. This method is called seismic data inversion. I have also shed light on the most widely used Kirchhoff's theory for scattering also called the Tangent theory. The results of this theory referred to as a forward model calculates the reflection coefficient based on surface parameter input and have been verified using the modeling tool OASES for different topologies.