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Topic: Subsidence craters

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	DOE - NNSA/NSO -- Photo Library Craters
		Underground testing often leaves visible evidence on the surface in the form of subsidence craters in varying dimensions.
		Subsidence craters are depressions on the surface that occur when the roof of the blast cavity collapses into the void left by the explosion.
		The size of the subsidence crater depends on the yield of the device, the depth of emplacement, and the geological characteristics of the surrounding soil.
	www.nv.doe.gov /library/photos/craters.aspx (97 words)

	Top Literature - Subsidence crater
		A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion.
		Many such craters are present at the Nevada Test Site, which is no longer in use for nuclear testing.
		Subsidence craters are created as the "roof" of the cavity caused by the explosion collapses.
	encyclopedia.topliterature.com /?title=Subsidence_crater (184 words)

	Mývatn-Askja
		On 15 February 1875 a subsidence was observed in the SE corner of the caldera.
		This crater was long believed to be the main vent of the 1875 eruption, despite early observations which clearly show that this was not the case.
		This subsidence was caused by the depletion of the water reservoir, a phenomena commonly observed in heavily exploited geothermal areas.
	www.norvol.hi.is /html/geol/trip3.html (4696 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		Subsidence is a term used in geology, engineering and surveying to denote the motion of a surface (usually, the earth's surface) downwards relative to a datum such as sea-level.
		This coupled with the large clear area adjacent to L block and the fact that the university is built over mine shafts led to an urban legend that the block sank into the ground due to a collapse of a mine tunnel.
		Subsidence generally causes high air pressure as more air moves into the same space: the polar highs are areas of almost constant subsidence, as are the horse latitudes, and these areas of subsidence are the sources of much of the world's prevailing wind.
	www.worldhistory.com /search.php?ix=wiki4&rf=0,PN2,P3,PN4,P6&page=1&type=article&hpp=&lfs=1&q=Subsidence (986 words)

	What Are the Real Yields of India's Tests?
		The wide shallow crater produced (reportedly it had a 47 m radius and was 10 m deep; recent high resolution commercial satellite imagery indicates a crater radius of 60 m) is also characteristic of a marginal cratering explosion rather than a contained subsurface detonation.
		True subsidence craters have dimensions similar to the underground cavity, which for this yield range would be a radius of 30 m or less.
		Palanquin was a deep cratering shot that excavated a 73 m by 24 m crater with an ejecta boundary extending 82 m from the center [Gibson 1965; pg.
	nuclearweaponarchive.org /India/IndiaRealYields.html (6788 words)

	Subsidized Stafford Loan (Site not responding. Last check: 2007-11-05)
		destroyed by subsidence and shear.]] Subsidence is a term used in geology, engineering and surveying to denote the motion of a surface (usually, the earth's surface) downwards relative to a datum such as sea-level.
		This type of subsidence can result in sinkholes which can be many hundreds of metres deep and can provide areas of ecological isolation which see the evolution of new branches of animal and plant.
		In reverse, or thrust, faults, relative subsidence may be measured in the hangingwall.
	www.wwwtln.com /finance/173/subsidized-stafford-loan.html (673 words)

	subsidence - Hutchinson encyclopedia article about subsidence (Site not responding. Last check: 2007-11-05)
		Subsidence is usually due to the removal of material from below the surface, and can be caused by faults, erosion, or by human activities such as mining.
		Under the influence of a great mental and moral upheaval, his character and his habits had taken on the appearance of complete change, but after a while with the subsidence of the storm, both began to settle toward their former places.
		With the subsidence of Esmeralda the lioness renewed her efforts to wriggle her huge bulk through the weakening lattice.
	encyclopedia.farlex.com /subsidence (180 words)

	A nuclear family vacation. - By Nathan Hodge and Sharon Weinberger - Slate Magazine (Site not responding. Last check: 2007-11-05)
		The landscape of Yucca Flat is now dotted with subsidence craters—saucer-shaped formations caused by the vaporization and collapse of rock hundreds of feet underground.
		The United States concluded the last full-scale underground test of a nuclear weapon in 1992 and declared an official moratorium in 1994 (the prefabricated towers for Icecap and Gabbs, nuclear tests scheduled for 1993, are still in place).
		The topography of craters is a reflection of a weapons designer's skill, he says.
	www.slate.com /id/2122382/entry/2122387 (1313 words)

	Crater Classification (Site not responding. Last check: 2007-11-05)
		Where possible, craters are classified using the five-grade system devised by Ralph Baldwin.
		Young craters, from impacts after the formation of the Maria, with the steepest, sharpest walls.
		Craters which have been partly obscured by flooding with lava at the time of the formation of the Maria.
	www.inconstantmoon.com /not_clas.htm (95 words)

	ch7.1
		The few craters that have formed on the subsided surface compare in density to the craters formed on the cluster (arrow) of Aristarchus secondary impact craters and associated herring- bone ridges; comparable ages for the Aristarchus secondary features and the depression are thus indicated.
		The subsidence was triggered either by the ground shock or seismic wavetrain generated when Aristarchus was formed 300 km to the west, or by the impacts of the secondary features.
		Craters containing bulbous material (arrows 2) that may be lavas extruded through the brecciated crater floor are visible.
	www.hq.nasa.gov /office/pao/History/SP-362/ch7.1.htm (1853 words)

	CRATERS: THEIR ORIGIN AND CLASSIFICATION (Site not responding. Last check: 2007-11-05)
		In July 1963, a crater about 1 foot deep, 8 feet in diameter, with a hole in the centre about 3 feet deep was found on the boundary between a potato field and a barley field at Manor Farm, Charlton, Wiltshire (near Shaftesbury, Dorset).
		The crater was discovered by farmer Roy Blanchard, according to Robert Chapman, (1) or by a Mr Reg Alexander, according to Leonard Cramp.
		The Charlton crater affair is a particularly interesting case in that study of the literature on the subject shows up the irrational and unscientific attitudes which prevail among British ufologists, even including those who are intelligent enough to know better.
	www.magonia.demon.co.uk /arc/70/craters.htm (2002 words)

	Distribution and Origin of Lunar Craters (Site not responding. Last check: 2007-11-05)
		The fact that craters appear to have been the product of slow and gentle processes does not, in my view, invalidate my hypothesis.
		Certainly the large craters stem from subsidence, and, as on Earth, the initiating upwards push may not necessarily have been explosive in every case.
		Moore's suggestion of gentle uplift and subsidence, repeated several times, fits in well with patterns of history in terrestrial volcanic foci, but, as on Earth, one must expect no uniformity of detailed history, and I do not think point-focus explosion can be ruled out, entirely, because of the objection made.
	www.nature.com /nature/journal/v197/n4864/abs/197273b0.html (177 words)

	Calderas
		Subsidence calderas are features that form subsequent to large eruptions that lower the level of magma in a chamber to the point that the chamber's roof can no longer support itself and collapses.
		These are large blast craters formed from the violent explosions of volcanoes, usually andesitic in composition.
		The final, most complex, type of caldera is the subsidence calderas that form in the marginal and epicontinental zones of an orogenetic belt.
	www.mindspring.com /~koz/papers/caldera.html (1512 words)

	Pokhran - India Special Weapons Facilities
		Although the absolute values of the explosive yield of the tests are not reliably known, their relative magnitude is, leading to an expectation of subsidence craters from the larger of the 1998 tests that are comparable to that of the 1974 test.
		Although the test area presents a surprisingly jumbled appearance, it would appear that the subsidence crater has a depth of about 10-15 meters, and a radius of somewhat over 30-40 meters [though the radius is difficult to estimate from available ground-truth photography].
		These two photographs disclose that the small subsidence crater from the test was centered on a long shed [#1], and that a pair of parallel sheds {#2 & #3] ran at right angles to this shed.
	www.globalsecurity.org /wmd/world/india/pokharan-pir.htm (2664 words)

	Final Environmental Impact Statement for the Nevada Test Site and Off-Site Locations
		The major unavoidable effects of underground testing include the release of large quantities of radioactivity into the subsurface, the formation of new subsidence craters, and the generation of ground motion that might be felt outside the boundaries of the NTS.
		Subsidence craters alter the natural surface drainage and might locally increase soil erosion.
		Preferential drainage from subsidence craters down the rubble chimney to the shot cavity might occur and might contaminate the groundwater as a result, although little data exist to determine whether this is the case.
	globalsecurity.org /wmd/library/report/enviro/eis-0243/eis0243_55.html (7036 words)

	NEVADA TEST SITE - United States Nuclear Forces
		The Area 9 sanitary landfill is located in a subsidence crater formed as a result of a subsurface nuclear detonation in the early 1960s.
		Two of the earliest shallow nuclear cratering experiments conducted at the NTS were detonated in 1951 and 1955 at this location.
		It left a large throw-out crater with a diameter of 390 m (1,280 ft) and a depth of 98 m (320 ft).
	www.fas.org /nuke/guide/usa/facility/nts.htm (8202 words)

	NTS Area 3 (Site not responding. Last check: 2007-11-05)
		Waste disposed in subsidence craters formed by the underground detonation of nuclear weapons
		Crater U-3ax/bl inactive and covered since January 1988
		Two additional craters, U-3az and U-3bg, are reserved for future disposal
	web.em.doe.gov /lfrg/ntsarea3.html (65 words)

	N. Tribe & Associates Ltd.
		This document will describe a method of plugging mine shafts, ventilation raises and mine cave subsidence which has been designed, tested and found to be successful, meets environmental requirements and has not failed in over 280 reclamation sites.
		The matte is made up of a number of highway truck tires linked together by cable and is sufficient large to cover the area of subsidence and a minimum of one meter onto stable rock on all sides.
		This opening lead to the underground workings and the surface crater was over 30 meters (100 feet) across.
	members.shaw.ca /nta/nltribe (2041 words)

	0282: U.S. Department of Energy
		The crater is 320 feet deep and 1280 feet in diameter.
		These craters are a result of the detonation of explosives during the testing at NTS.
		U.S. 0017 Another view of Sedan Crater formed July 6, 1962, by a test in the Atomic Energy Commission's Plowshare Program to develop peaceful uses for Nuclear explosives.
	library.nevada.edu /speccol/photographs/0282_USdoe.html (949 words)

	Nevada Division of Environmental Protection - Bureau of Federal Facilities - Underground Nuclear Testing
		Many of the underground tests left subsidences craters varying in diameter and depth.
		Sedan Crater: Sedan Crater was formed with a 100 kiloton nuclear explosive devise -- the devise was buried 635 feet below the desert alluvium.
		The crater is on the National Register of Historic Places and is visible from space.
	ndep.nv.gov /boff/photo02.htm (244 words)

	Determining the age of surfaces on Mars
		So craters are not uniformly distributed on Mars; instead, there are a few areas with significant numbers of very large craters (greater than 300 km in diameter), most of the rest of the southern highlands have only smaller craters, and all of the northern lowlands have very few craters.
		Other processes like subsidence or erosion are also possibilities, but these would have had to work differently in some areas than others, and this is not likely -- on the Earth, these forces have destroyed craters everywhere simultaneously.
		The area in the north with no craters on it must have be resurfaced after the Hesperian ended, since otherwise many craters would have been formed on it.
	www.msss.com /http/ps/age2.html (1186 words)

	Comments on: Hyperion! (Site not responding. Last check: 2007-11-05)
		I don't believe the large crater that you refer to is an impact crater as it looks more like a huge subsidence as you can see the craters that were on the edge of the subsidence have been elongated when the surface dropped.
		As for the fl stuff on the bottom of the craters after fooling around with the image in photoshop it appears to be more like some sort of stain rather than extra material covering the bottom of the crater.
		I wonder… that crater is nearly the size of the moon.
	www.badastronomy.com /bablog/2005/10/18/hyperion/feed (378 words)

	Underground Nuclear Weapons Testing
		After a period of minutes to hours, as the gases in the cavity cool, the pressure subsides and the weight of the overburden causes the cavity roof to collapse, producing a vertical, rubble-filled column known as a rubble chimney.
		The rubble chimney commonly extends to the ground surface, forming a subsidence crater.
		Subsidence craters generally are bowl-shaped depressions with a diameter ranging from about 60 to 600 m (200 to 2,000 ft) and a depth ranging from a few meters up to 60 m (200 ft), depending on the depth of burial and the explosive energy yield.
	www.fas.org /nuke/intro/nuke/ugt-nts.htm (1841 words)

	CLUI - Newsletter
		Every hour, Coach USA buses left to take visitors to Sedan Crater, far into the forward area of the test site (a planned stop at Frenchman's Flat, perhaps the premier attraction on the NTS, was cancelled because the ground was too wet from the snowstorm for the buses).
		It was formed by the first Plowshare test, which explored the possible uses of nuclear devices for peacetime projects, such as earth moving and cratering to create harbors, canals, and mountain passes.
		On the return trip from Sedan, we saw evidence of the NTS's past in the distance - domestic test structures from 1950s tests, subsidence craters marked with orange fencing, and towers from which test devices were to be lowered into deep, drilled shafts.
	www.clui.org /clui_4_1/lotl/001spsu/001spsu3a.html (1540 words)

	Long-Term Stewardship, Nevada Test Site
		They resulted in hundreds of subsidence craters and caused contamination of the subsurface geologic media, surface soils, and groundwater over an estimated 300 square mile area.
		In terms of cumulative effects, the contamination from above ground testing along with the safety shots and cratering events left an estimated 27,000 acres (42 square miles) of surface soils contaminated at levels in excess of 40 pico curies per gram.
		The site is comprised of four subsidence craters with areas between the craters excavated to make two oval-shaped landfill units.
	www.state.nv.us /nucwaste/nts/steward.htm (4188 words)

	Ground Collapse Over Abandoned Mines
		Geologic and mining conditions differ in the Centerville area (Appanoose County) and few subsidence incidents are known, though the potential for them exists.
		Subsidence in rural areas affects pasture and row crops, and reduces the land area available for agriculture.
		We need to be more aware of the problem, document subsidence events when they occur, take remedial action where possible, and utilize available information in land-use planning.
	www.igsb.uiowa.edu /browse/minecoll/minecoll.htm (254 words)

	Subsidence
		A -destroyed-by-subsidence-and- destroyed by subsidence and shear">road destroyed by subsidence and shear In geology, engineering, and surveying, subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level.
		The opposite of subsidence is uplift, which results in an increase in elevation.
		1.4 Subsidence caused by extraction of natural gas
	www.kiwipedia.com /subsidence.html (83 words)

	Nuclear Testing at the Nevada Test Site (Site not responding. Last check: 2007-11-05)
		In the instant after the device detonates—destroying itself and everything in the test shaft—the cables relay critical measurements back to weapons scientists, allowing them to ascertain the device's yield, efficiency, and other characteristics.
		Note the subsidence craters from previous tests in the vicinity.
		Underground nuclear tests leave subsidence craters of vary dimensions depending on the yield of the device detonated, the depth of emplacement, and the geological characteristics of the surrounding soil.
	www.brook.edu /fp/projects/nucwcost/nts.htm (630 words)

	Recharge from a Subsidence Crater at the Nevada Test Site -- Wilson et al. 64 (5): 1570 -- Soil Science Society of ...
		More than 400 nuclear subsidence craters exist at the NTS (Tyler et al., 1992).
		The playa region of the crater was visibly distinguished by
		5 Diagrams showing the domain and mesh for the simulations representing (a) original crater surface to the water table, and (b) present crater surface with sediment soil properties shown in (c) in which numbers refer to hydraulic properties listed in Table 3.
	soil.scijournals.org /cgi/content/full/64/5/1570 (6294 words)

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