Title

Applying Quasi-Digital Seismic Data Obtained from Paper Seismic Traces to Analyze the Geology of Flathead Valley, MT, USA

Presentation Type

Poster

Abstract

Flathead Lake is located in southern Flathead Valley in northwest Montana. Flathead Valley and its southern extension, the Mission Valley, are both tectonic half-grabens that are part of the seismically-active northern Basin and Range province. Being located in the center of an active seismic zone, the sediments under Flathead Lake contain a great archive of the historic and pre-historic seismic activity. To unravel this seismic archive, I analyzed a set of seismic reflection data that was acquired in the 1970s and 80s. The seismic surveys were conducted on the lake, their goal to map the major normal fault structures that define the basin and to map the lacustrine and glacial deposits. At this time, data were collected on paper traces using analog instruments, rendering an interpretation of the subsurface difficult and inaccurate.

With the advent of more sophisticated computer technology and software, however, I was able to digitize this paper data set and interpret it in a fully digital environment. The process I utilized takes image scans of the paper traces and translates them quasi-seismic digital traces. Applying geophysical processing methods, such as band-pass filtering, further yields traces with an oscillatory character similar to that of real seismic traces. Spatial referencing for the traces was determined by recovering survey line endpoints using GIS, and the UTM coordinates were added as metadata. A small subset of lines was imported into a 3-D computer environment, something that could never have been done with only analog data.

This workflow process enabled me to identify and remove noise features, which was not possible using manual methods and may have contributed to some error in previous interpretations of the data. I was also able to interpret the timing, magnitude, and location of the Flathead Lake subsurface faults and compare my findings to the previous literature.

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Apr 12th, 3:00 PM Apr 12th, 4:00 PM

Applying Quasi-Digital Seismic Data Obtained from Paper Seismic Traces to Analyze the Geology of Flathead Valley, MT, USA

UC Ballroom

Flathead Lake is located in southern Flathead Valley in northwest Montana. Flathead Valley and its southern extension, the Mission Valley, are both tectonic half-grabens that are part of the seismically-active northern Basin and Range province. Being located in the center of an active seismic zone, the sediments under Flathead Lake contain a great archive of the historic and pre-historic seismic activity. To unravel this seismic archive, I analyzed a set of seismic reflection data that was acquired in the 1970s and 80s. The seismic surveys were conducted on the lake, their goal to map the major normal fault structures that define the basin and to map the lacustrine and glacial deposits. At this time, data were collected on paper traces using analog instruments, rendering an interpretation of the subsurface difficult and inaccurate.

With the advent of more sophisticated computer technology and software, however, I was able to digitize this paper data set and interpret it in a fully digital environment. The process I utilized takes image scans of the paper traces and translates them quasi-seismic digital traces. Applying geophysical processing methods, such as band-pass filtering, further yields traces with an oscillatory character similar to that of real seismic traces. Spatial referencing for the traces was determined by recovering survey line endpoints using GIS, and the UTM coordinates were added as metadata. A small subset of lines was imported into a 3-D computer environment, something that could never have been done with only analog data.

This workflow process enabled me to identify and remove noise features, which was not possible using manual methods and may have contributed to some error in previous interpretations of the data. I was also able to interpret the timing, magnitude, and location of the Flathead Lake subsurface faults and compare my findings to the previous literature.