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Grand Teton National Park Report

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The Teton normal fault, Wyoming, is characterized by a 55-km long fault scarps of postglacial age (< 14,000 yrs.). These well developed late Quaternary scarps range in height from 3 to 52 m (Smith et al., 1993; Byrd et al., 1994) and have been the locus of several large, scarpforming earthquakes. The Teton fault is located in a tectonically active area of the Intermountain Seismic Belt but occupies a notable gap in the seismicity and is considered a major earthquake hazard to the region. The Teton fault is, therefore, considered a location of future large earthquakes with accompanying strain accumulation that may be measured by accurate measurements of changes in ground height, which has been the objective of our 1993 and past Teton fault leveling surveys. A 1st-class, 1st-order level line was established across the Teton fault in Grand Teton National Park in 1988 and has been observed in 1989, 1991, and 1993 to assess long-term deformation. This document is a progress report of the . most recent re-observations of the level line conducted in August, 1993.