Summary Information for Field Activity 1986-010-FA

Area of Operations: Jackson Lake, Wyoming, United States, North America

Dates: July 07, 1986 to July 23, 1986

Chief scientist: Steve Colman

   Ken Pierce (Co-Ch. Sci.)

Objectives: Collection of high-resolution seismic reflection, bathymetry, and sidescan sonar data and cores to find and interpret submerged shorelines in Jackson Lake. The lake occupies a tectonic basin dominated by an active, high-angle normal fault along the western margin of the lake and the eastern side of the Teton Range. Each major fault displacement apparently results in subsidence of the lake basin and tilting to the west. These earthquake events should be recorded by successive submerged, westward-tilted shorelines.

Type of Activity: Sampling; Seismic profiling; Sea floor mapping;Sea floor mapping

Information to be derived: Sea floor map; Morphology;

Summary: Although plagued by bad weather, difficult logistics, and navigation problems, the cruise was generally successful. Submerged shoreline features were clearly observed on both the seismic and sidescan sonar records. Interpretation and mapping of these features will be required before these features can be related to earthquake events. Coring efforts were only partially successful; cores of Holocene lake clay were recovered, but this material was generally stiff and difficult to penetrate. No cores reached underlying coarser material associated with the submerged shorelines. Shadowing by islands and peninsulas was a problem for navigation signals, but generally signals from at least two stations were received. Distances from the navigation stations were recorded both by hand and on cassette tape. Fitting all of the geophysical equipment on board a 19-ft. vessel required creative deployment, but the equipment mostly performed well. The ORE power supply had intermittent problems apparently related to its cover interlock switch. No time was lost to equipment failure.

Contact: Steve Colman (scolman@usgs.gov)

InfoBank: uses the identifier J-1-86-WY. Visit this site for more information.

InfoBank: uses the identifier J-1-86-WY. Visit this site for more information.

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