Art Explosion 800 000
Colby DuLin
One of the most common questions asked of YVO is "when is the next big one?" This is an interesting question, given the multiple potential natural hazards that exist at Yellowstone. Big earthquake? Big lava flow? Big explosion?
Most people mean the big explosion, but that's not a particularly likely event. In fact, most people do not know about the potential hazard associated with a hydrothermal (hot water) explosion, which is far more common than any eruption of lava or volcanic ash.
Hydrothermal explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments. The explosions can reach heights of 2 km (1.2 miles) and leave craters that are from a few meters (tens of feet) up to more than 2 km (1.2 mi) in diameter. Ejected material, mostly breccia (angular rocks cemented by clay), can be found far as 3 to 4 km (1.8 to 2.5 mi) from the largest craters.
Hydrothermal explosions occur where shallow interconnected reservoirs of fluids with temperatures at or near the boiling point underlie thermal fields. These fluids can rapidly transition to steam if the pressure suddenly drops. Since vapor molecules take up much more space than liquid molecules, the transition to steam results in significant expansion and blows apart surrounding rocks and ejects debris. Hydrothermal explosions are a potentially significant local hazard and can damage or even destroy thermal features. In Yellowstone, hydrothermal explosions occur within the Yellowstone Caldera and along the active Norris-Mammoth tectonic corridor.
Large hydrothermal explosions occur on average every 700 years, and at least 25 explosion craters greater than 100 m (328 ft) wide have been identified. The scale of these craters dwarfs similar features in geothermal areas elsewhere in the world. Large hydrothermal explosions in Yellowstone occurred after an icecap greater than 1 km (0.6 mi) thick receded from the Yellowstone Plateau around 14,000-16,000 years ago.
Studies of large hydrothermal explosion events in Yellowstone indicate: (1) none are directly associated with magma; (2) several smaller historic explosions have been triggered by seismic events, like the 1959 Hebgen Lake earthquake; (3) rocks ejected by hydrothermal explosions show significant mineral alteration, indicating that explosions occur in areas subjected to intense hydrothermal processes; and (4) many large hydrothermal explosion craters in Yellowstone are similar in area to active geyser basins and thermal areas.
Critical components for development of large hydrothermal systems require high heat flow, abundant water (Yellowstone Plateau receives about 180 cm (70 in) of precipitation annually), and seismicity (Yellowstone experiences 1000-3000 earthquakes/year) to maintain open fractures. Active deformation of the Yellowstone Caldera and seasonal changes also contribute.
Hydrothermal systems with explosive potential have a water-saturated system at or near boiling temperatures and an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow. Ascending hydrothermal fluids flow along fractures that have developed due to repeated inflation and deflation of the caldera, which causes rocks to break, and along edges of low-permeability rhyolitic lava flows. The size and location of hydrothermal fields may be limited by excessive alteration of rocks and development of clay minerals that can create caprocks and seal the system. If a portion of the system is sealed, any sudden or abrupt drop in pressure causes water to flash to steam, which is rapidly transmitted through interconnected fractures. The result is a series of multiple explosions and the excavation of a crater. Similarities between the size and dimensions of large hydrothermal explosion craters and thermal fields in Yellowstone indicate that this type of event may be an end stage in geyser basin evolution.
Although large hydrothermal explosions are rare events on a human time scale, the potential for additional future events of the sort in Yellowstone National Park is not insignificant. Based on the occurrence of large hydrothermal explosion events over the past 16,000 years, an explosion large enough to create a 100-m- (328-ft-) wide crater might be expected every few hundred years.
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The hydrogen from the red giant accretes on the surface of the white dwarf, causing a buildup of pressure and heat. Eventually, it triggers a thermonuclear explosion big enough to blast away that accreted material. For T CrB, that event appears to reoccur, on average, every 80 years.
The T CrB nova was last seen from Earth in 1946. Its behavior over the past decade appears strikingly similar to observed behavior in a similar timeframe leading up to the 1946 eruption. If the pattern continues, some researchers say, the nova event could occur by September 2024.
Dr. Elizabeth Hays, chief of the Astroparticle Physics Laboratory at NASA Goddard, agreed. She said part of the fun in preparing to observe the event is seeing the enthusiasm among amateur stargazers, whose passion for extreme space phenomena has helped sustain a long and mutually rewarding partnership with NASA.
Eastward-looking aerial photograph of Port Chicago Naval Magazine, early 1944. The town of Port Chicago is visible in the upper right. At lower left, the utility and personnel piers extend toward the two sections of Seal Island. The munitions loading pier curves to the left beyond the revetments, between which railcars loaded with munitions were shunted. The munitions pier is separated from the barracks buildings near the personnel pier and near the town by marshy tidal zones (U.S. Navy/National Park Service).
Diagram from the Port Chicago board of inquiry's report showing the facility's munitions pier at the time of the disaster. Clearly delineated are the two cargo ships, E. A. Bryan and Quinault Victory, the three lines of railcars, and the placement and quantities of various types of munitions (antiaircraft ammunition of various calibers, several types of aerial bombs, high explosive for underwater munitions) (U.S. Navy).
While the court of inquiry was still pursuing its investigation, events that occurred less than a month after the Port Chicago explosions kept the tragedy in the public eye. They also imbued the event with notoriety and controversy, and would ultimately remain unresolved until the end of the 20th century.
Online documents collection: includes initial U.S. Navy incident findings, the Navy court of inquiry report, Port Chicago Naval Magazine war diary, various official correspondence, and a period press release
Bibliography: includes a broad spectrum of published secondary and unpublished archival sources related to the Port Chicago tragedy and its aftermath, and to the service of African Americans in the U.S. Navy and other armed forces branches during World War II
Port Chicago Naval Magazine, California: Damage resulting from the 17 July 1944 ammunition explosion. This view looks southwest, showing collapsed Building A-14 (Garage) in the center. Photograph was taken by the Mare Island Navy Yard (NH 96824).
This view looks south from the munitions pier, showing the wreckage of Building A-7 (Joiner Shop) at the right. There is a piece of twisted steel plating just to left of the long pole in left center. Photograph was taken by the Mare Island Navy Yard (NH 96821).
This view looks north from barricade magazine BM-138. The badly munitions pier is in the background with the remains of SS Quinault Victory barely visible off its tip (right distance). Note crushed roofs on Southern Pacific railway cars in the foreground, damaged automobile at left, railway crane in center, Marine sentry at right armed with a Reising .45-caliber submachine gun, and magazine door below the sentry. Photograph was taken by the Mare Island Navy Yard (NH 96822).
This view of the effects of the 17 July 1944 explosions looks north, showing the wreckage of Building A-7 (Joiner Shop) in the center and munitions pier beyond. Note bulldozer and damaged automobiles in the foreground, railway crane at left, and scattered pilings. Photograph was taken by the Mare Island Navy Yard (NH 96823).
An explosion is a rapid expansion in volume of a given amount of matter associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Explosions may also be generated by a slower expansion that would normally not be forceful, but is not allowed to expand, so that when whatever is containing the expansion is broken by the pressure that builds as the matter inside tries to expand, the matter expands forcefully. An example of this is a volcanic eruption created by the expansion of magma in a magma chamber as it rises to the surface. Supersonic explosions created by high explosives are known as detonations and travel through shock waves. Subsonic explosions are created by low explosives through a slower combustion process known as deflagration.
For an explosion to occur, there must be a rapid, forceful expansion of matter. There are numerous ways this can happen, both naturally and artificially, such as volcanic eruptions, or two objects striking each other at very high speeds, as in an impact event. Explosive volcanic eruptions occur when magma rises from below, it has dissolved gas in it. The reduction of pressure as the magma rises causes the gas to bubble out of solution, resulting in a rapid increase in volume, however the size of the magma chamber remains the same. This results in pressure buildup that eventually leads to an explosive eruption. Explosions can also occur outside of Earth in the universe in events such as supernovae, or, more commonly, stellar flares. Humans are also able to create explosions through the use of explosives, or through nuclear fission or fusion, as in a nuclear weapon. Explosions frequently occur during bushfires in eucalyptus forests where the volatile oils in the tree tops suddenly combust.[1]
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