Geologic effects of the Rainier underground nuclear explosion : a summary progress report of U.S. Geological Survey investigations

Abstract

This report is a summary of U. S. Geological Survey investigations of the geological effects of the Rainier underground nuclear explosion which was detonated at the Atomic Energy Commission's Nevada Test Site on September 19, 1957. The 1.7 kiloton explosion took place 900 feet below the surface of the ground at the end of a tunnel driven into volcanic tuff of the Oak Spring formation. The rocks close to the explosion point were white to brown pumiceous rhyolitic tuffs that contain phenocrysts of quartz and feldspar biotite and xenoliths of older rocks embedded in a fine-grained matrix of heulandite, clay, ,^-cristobalite, and amorphous material. Unconnected open vesicles make up to 11.5 percent by volume of the rocks. In the natural state these rocks have an average porosity of 24 percent, a bulk density of 2.0, a water content of 14 percent by weight, an acoustic velocity of 8,300 feet per second, a coppressive strength of roughly 4,000 psi at atmospheric pressure, and a tensile strength of roughly 100 psi. Under confining pressures greater than 10,000 psi the tuff will deform at least 20 percent with a consequent increase in density of about 8 percent.Exploration of the rocks disturbed by the explosion has been carried out by one vertical hole and 3 near-horizontal holes and by tunneling toward the point of the explosion. This exploration has revealed a breccia zone extending 70 feet from the explosion chamber. The breccia contains radioactive glass, angular to subrounded blocks, 0.3 to 3 feet across in a

Underground Nuclear Detonations

“…The airb1ast effects for all shots at scaled depth The details of fracturing and bedding plane shifts were mapped and have been described elsewhere [Diment and others 1959 Seismic signals from the Rainier event were detected at various stations in the contin~·ntal U.S. and at distances up to 1000 miles [Diment andothers 1959, Carder andothers 1958]. Seismic signals were also detected (though barely resolved) at College Station in Fairbanks, Alaska at a distance of 2200 mile~:;.…”

Some effects of underground nuclear explosions on tuff

“…and Blanca underground nuclear explosions on the tuffaceous rocks that surround the shot chambers. Reports on some of these investigations have been written by Gibbons (1958), McKeown and others (1958), and Diment and others (1959). The effects of these shots will be described in the following order: Those observed on the surface, in the underground workings and core holes, and, finally, the preliminary results from laboratory investigations of the affected tuffs.…”

Perched ground water in zeolitized-bedded tuff, Rainier Mesa and vicinity, Nevada test site, Nevada

“…Selected references are Cattermole and Hansen (1962), Hansen and others (1963), Diment andothers (1958a and1958b), McKeown and Dickey (1961), Dickey and Emerick (1961), , Emerick and Dickey (1962), and Laraway and Houser (1962).…”

“…The Ul2b tunnel was driven above the main zone of saturation, which contains the water-bearing fractures. In three drifts in the Ul2b tunnel--Ul2b.01, U12b.03 and Ul2b.04--the average interstitial porosity of the zeolitic tuff ranges from 27 to 29 percent (Diment andothers, 1959a and1959b). The average interstitial permeability to fresh water was 0.2 gpd/ft 2 , but to brine was only 0.03 gpd/ft 2 .…”