Presentation Type

Poster

Abstract

On several seismic lines from the Flathead Lake Seismic Data signal, arrival patterns exhibited curving shapes that might indicate they are diffraction arrivals. This project attempted to resolve whether those patterns were the result of diffracted energy or were true reflections from subsurface features. Approximately 25 seismic lines were generated during the 1970 Flathead seismic survey and are stored online via the University of Montana Scholar Works site. I catalogued locations along various lines that fit the visual criteria for diffraction arrivals, and utilized computational engines (Python, and Awk) to calculate suites of diffraction curves taking into account the possible distribution of seismic velocities in the lake water and the underlying sediments. I calculated a suite of diffraction curves and overlaid them on actual seismic sections to assess whether or not the curving arrivals in the data matched the predicted curves, Seismic Unix tools were used for the overlay comparison. For those lines where the curves overlay, the events in the data were interpreted to be diffractions. Migration, using Seismic Unix tools, was applied in an attempt to remove the curving patterns. Despite the age of the dataset, no systematic and quantitative analysis of the diffraction-like patterns has ever been done. In 1970, University of Montana facilities lacked computational resources and seismic processing tools for the analysis and correction of the diffractions. In addition, the embryonic nature of digital migration in the era of the Flathead Lake Seismic survey prevented a study of this type from being completed. During the initial Flathead Lake Seismic Survey the data were recorded analog and not digital. The digital data that I have used are the result of a 2012 image to data conversion process. The analysis and migration processing clear up some interpretation questions and provide a clearer view of the true reflections from the sediments.

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Physical Sciences

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Apr 17th, 3:00 PM Apr 17th, 4:00 PM

Extracting New Periglacial Lacustrine Information from the 1970 Flathead Lake Seismic Survey Data

South UC Ballroom

On several seismic lines from the Flathead Lake Seismic Data signal, arrival patterns exhibited curving shapes that might indicate they are diffraction arrivals. This project attempted to resolve whether those patterns were the result of diffracted energy or were true reflections from subsurface features. Approximately 25 seismic lines were generated during the 1970 Flathead seismic survey and are stored online via the University of Montana Scholar Works site. I catalogued locations along various lines that fit the visual criteria for diffraction arrivals, and utilized computational engines (Python, and Awk) to calculate suites of diffraction curves taking into account the possible distribution of seismic velocities in the lake water and the underlying sediments. I calculated a suite of diffraction curves and overlaid them on actual seismic sections to assess whether or not the curving arrivals in the data matched the predicted curves, Seismic Unix tools were used for the overlay comparison. For those lines where the curves overlay, the events in the data were interpreted to be diffractions. Migration, using Seismic Unix tools, was applied in an attempt to remove the curving patterns. Despite the age of the dataset, no systematic and quantitative analysis of the diffraction-like patterns has ever been done. In 1970, University of Montana facilities lacked computational resources and seismic processing tools for the analysis and correction of the diffractions. In addition, the embryonic nature of digital migration in the era of the Flathead Lake Seismic survey prevented a study of this type from being completed. During the initial Flathead Lake Seismic Survey the data were recorded analog and not digital. The digital data that I have used are the result of a 2012 image to data conversion process. The analysis and migration processing clear up some interpretation questions and provide a clearer view of the true reflections from the sediments.