Geological and Seismological Investigations at Ririe Dam, Idaho
Abstract
Geological and seismological studies were conducted at Ririe Dam in south eastern Idaho to identify and define potential seismic hazards at the site and beyond. The geological investigations at the site concentrated on interpreting two significant displacements in basalt flows in the embankment foundation, which formerly had been classed as faults. Core drilling was conducted at the downstream toe of the dam to gather additional data. Core drill data plus data obtained from field observations were integrated with data from previous exploration programs and evaluated using structural contour and isopach techniques. These evaluations resulted in the conclusion that the offsets in the basalts were due, in one case, to a landslide and, in the other, to topography; no active or capable faults are present under the dam or in the immediate vicinity. Faulting and historic seismicity were investigated within a radius of approximately 200 km of the site. Aerial photography, LANDSAT imagery, and aerial overflights were a part of the regional fault studies. The regional fault studies indicated that active or capable faults were present in the Yellowstone National Park (YNP) area. Nearby faults, such as the Grand Valley and Snake River faults east of the site, were not considered to be active or capable.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1981
- Accession Number
- ADA104833
Entities
People
- Charlie B. Whitten
- David M. Patrick