Danny Boy Event, Project 1.6, Mass Distribution Measurements of Crater Ejecta and Dust, POR 1815 (WT) PDF Download
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Author: Landon K. Davis Publisher: ISBN: Category : Blast effect Languages : en Pages : 56
Book Description
The results of various previously reported investigations of the Danny Boy event are utilized to compute and compare the volumes of ejected material and volumes attributable to other crater-formation mechanisms. Imbalance of the volumetric contributions is attributed primarily to the uncertainty of the ejecta density in the lip region. Approximately 65 percent of the rock material dissociated by the explosion was permanently ejected from the crater; less than 2 percent of the ejected material was deposited beyond 3 crater radii from ground zero. Comparisons are made with high-explosive and nuclear detonations in desert alluvium. (Author).
Author: A. D. Rooke (Jr) Publisher: ISBN: Category : Languages : en Pages : 112
Book Description
An array of tarpaulins was placed in a concentric circular pattern about the ground zero of a nuclear device with an intended yield of 470 tons. The device was detonated at a depth of 33.5 meters in a basalt medium. After the shot, when the residual radioactivity permitted, samples of ejecta and dust thrown from the crater and deposited on the tarpaulins were recovered, weighed, and analyzed for particle size. The nearest samples to GZ were recovered at a radial distance of 94 meters and the most remote at 268 meters. From a total of 158 collector stations, 27 samples were recovered. Mass distribution per unit area and size distribution were tabulated and shown graphically as functions of radial distance from GZ. The amount of deposition was found to decrease sharply with distance; most of the deposition was from within 150 meters of GZ. Particle size similarly decreased with distance from GZ, the percentage of fines increasing rapidly beyond the 94-meter collector ring. Results of similar experiments are summarized and compared with Danny Boy data by means of dimensionless plots. (Author).
Author: Landon K. Davis Publisher: ISBN: Category : Blast effect Languages : en Pages : 56
Book Description
The results of various previously reported investigations of the Danny Boy event are utilized to compute and compare the volumes of ejected material and volumes attributable to other crater-formation mechanisms. Imbalance of the volumetric contributions is attributed primarily to the uncertainty of the ejecta density in the lip region. Approximately 65 percent of the rock material dissociated by the explosion was permanently ejected from the crater; less than 2 percent of the ejected material was deposited beyond 3 crater radii from ground zero. Comparisons are made with high-explosive and nuclear detonations in desert alluvium. (Author).
Author: Michael Raymond Zanetti Publisher: ISBN: Category : Cratering Languages : en Pages : 0
Book Description
The formation of an impact crater ejecta blanket can be viewed as a form of organized chaos. Material that is ejected from a crater is heavily brecciated, but falls back to the surface along ballistic trajectories, generally preserving an inverted sense of the original stratigraphy. As the ejecta re-impacts the area surrounding the crater it forms a thick blanket of ejected material and reworked target surface that gradually thins away from the crater rim. Within the crater, crater modification processes, such as wall terrace formation and impact melt drainage, transform the crater in expectable ways. The approach adopted in this research is to use what is known about impact cratering and ejecta emplacement processes to geologically map craters on the Moon using remote-sensing data, determine the timing of individual impacts on the Moon, and investigate terrestrial impact melt glass. Research has been divided into three parts: 1) a detailed geomorphologic and geologic map of the lunar crater Aristarchus; 2) detailed crater size-frequency distribution measurements on the ejecta blankets of the lunar craters Aristarchus and Tycho; and 3) characterization of zircon decomposition in impact melt glass from the Mistastin Lake impact structure, Labrador, Canada. Mapping the geomorphology and geology of Aristarchus has shown that there are differences in the distribution of morphologic and compositional units related to pre-existing topography. I use the basic principles of inverted stratigraphy and remote-sensing data to investigate the geology of the subsurface material excavated by the crater and determine that Aristarchus likely excavated a buried pluton, or hypabyssal intrusive body, related to the large, possibly bi-modal, Cobra Head volcanic complex on the southern Aristarchus Plateau. Measuring crater size-frequency distributions on the ejecta blankets of Aristarchus and Tycho were done to determine the timing of these impacts; however, my measurements revealed that there is a significant difference in crater density, irrespective of crater diameter, between impact melt and ejecta blanket units. I show that the difference in crater density between these units can most likely be explained by a mechanism of self-secondary cratering, where late-arriving fragments of ejecta crater the surface of the ejecta blanket after it forms, but prior to the arrival of impact melt flows. These measurements call into question the long-held notion that ejecta blankets represent completely resurfaced units through ballistic sedimentation, free of impact craters immediately after formation, and these measurements suggest that cratering flux over the last billion years of the Solar System may be considerably lower. Lastly, I use field observations and a number of state-of-the-art laboratory analyses of a sample of impact melt glass from the Mistastin Lake impact structure to study the decomposition of zircon grains and the provenance of the impact melt. From my measurements, I show that zircon grains from a mangerite target rock were entrained in a superheated melt of very low viscosity and quenched, preserving high temperature mineral phases, and revealing how zircon grains undergo decomposition in a natural sample.
Author: R. H. Carlson Publisher: ISBN: Category : Languages : en Pages : 143
Book Description
For surface craters, 35 percent of the true crater mass was represented by ejecta, 40 percent by fallback, and 25 percent by compaction and distortion of the medium surrounding the crater. Ejected material represented about 88 percent of the apparent crater mass. The ratio of ejecta mass to true crater mass increased with burst depth, reaching a maximum of 0.58 at a burst depth of 1.2 feet. The fallback mass was approximately equal to the ejecta mass at a burst depth of about 6.4 feet.
Author: Landon K. Davis
Author: A. D. Rooke (Jr)
Author: Landon K. Davis
Author: Luke J. Vortman
Author: Eugene E. Addor
Author: Michael Raymond Zanetti
Author: 
Author: 
Author: A. D. Rooke
Author: R. H. Carlson
Author: United States. Army. Corps of Engineers