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Sandblow
Sand boils or sand volcanoes occur when water under pressure wells up through a bed of sand. The water looks like it is boiling up from the bed of sand, hence the name. Sand volcano A sand volcano or sand blow is a cone of sand formed by the ejection of sand onto a surface from a central point. The sand builds up as a cone with slopes at the sand's angle of repose. A crater is commonly seen at the summit. The cone looks like a small volcanic cone and can range in size from millimetres to metres in diameter. The process is often associated with soil liquefaction and the ejection of fluidized sand that can occur in water-saturated sediments during an earthquake. The New Madrid Seismic Zone exhibited many such features during the 1811–12 New Madrid earthquakes. Adjacent sand blows aligned in a row along a linear fracture within fine-grained surface sediments are just as common, and can still be seen in the New Madrid area. In the past few years, much effort has gone into the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christchurch Quake, 2011-02-22
Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / Ōtākaro flows through the centre of the city, with an urban park along its banks. The city's territorial authority population is people, and includes a number of smaller urban areas as well as rural areas. The population of the urban area is people. Christchurch is the second-largest city by urban area population in New Zealand, after Auckland. It is the major urban area of an emerging sub-region known informally as Greater Christchurch. Notable smaller urban areas within this sub-region include Rangiora and Kaiapoi in Waimakariri District, north of the Waimakariri River, and Rolleston and Lincoln in Selwyn District to the south. The first inhabitants migrated to the area sometime between 1000 and 1250 AD. They hunted moa, which led t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mud Volcano
A mud volcano or mud dome is a landform created by the eruption of mud or slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true igneous volcanoes as they do not produce lava and are not necessarily driven by magmatic activity. Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700 meters high and 10 kilometers wide. Smaller mud exudations are sometimes referred to as mud-pots. The mud produced by mud volcanoes is mostly formed as hot water, which has been heated deep below the Earth's surface, begins to mix and blend with subterranean mineral deposits, thus creating the mud slurry exudate. This material is then forced upwards through a geological fault or fissure due to local subterranean pressure imbalances. Mud volcanoes are associated with subduction zones and about 1100 have been identified on or near land. The temperature of any given active mud volcano generally r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1906 San Francisco Earthquake
At 05:12 Pacific Standard Time on Wednesday, April 18, 1906, the coast of Northern California was struck by a major earthquake with an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI (''Extreme''). High-intensity shaking was felt from Eureka on the North Coast to the Salinas Valley, an agricultural region to the south of the San Francisco Bay Area. Devastating fires soon broke out in San Francisco and lasted for several days. More than 3,000 people died, and over 80% of the city was destroyed. The events are remembered as one of the worst and deadliest earthquakes in the history of the United States. The death toll remains the greatest loss of life from a natural disaster in California's history and high on the lists of American disasters. Tectonic setting The San Andreas Fault is a continental transform fault that forms part of the tectonic boundary between the Pacific Plate and the North American Plate. The strike-slip fault is characterized by ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Francisco
San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of California cities by population, fourth most populous in California and List of United States cities by population, 17th most populous in the United States, with 815,201 residents as of 2021. It covers a land area of , at the end of the San Francisco Peninsula, making it the second most densely populated large U.S. city after New York City, and the County statistics of the United States, fifth most densely populated U.S. county, behind only four of the five New York City boroughs. Among the 91 U.S. cities proper with over 250,000 residents, San Francisco was ranked first by per capita income (at $160,749) and sixth by aggregate income as of 2021. Colloquial nicknames for San Francisco include ''SF'', ''San Fran'', ''The '', ''Frisco'', and '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ohio River
The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illinois. It is the third largest river by discharge volume in the United States and the largest tributary by volume of the north-south flowing Mississippi River that divides the eastern from western United States. It is also the 6th oldest river on the North American continent. The river flows through or along the border of six states, and its drainage basin includes parts of 14 states. Through its largest tributary, the Tennessee River, the basin includes several states of the southeastern U.S. It is the source of drinking water for five million people. The lower Ohio River just below Louisville is obstructed by rapids known as the Falls of the Ohio where the elevation falls in restricting larger commercial navigation, although in the 18th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mississippi River
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it flows generally south for to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian mountains. The main stem is entirely within the United States; the total drainage basin is , of which only about one percent is in Canada. The Mississippi ranks as the thirteenth-largest river by discharge in the world. The river either borders or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana. Native Americans have lived along the Mississippi River and its tributaries for thousands of years. Most were hunter-ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cairo, Illinois
Cairo ( ) is the southernmost city in Illinois and the county seat of Alexander County. The city is located at the confluence of the Ohio and Mississippi rivers. Fort Defiance, a Civil War camp, was built here in 1862 by Union General Ulysses S. Grant to control strategic access to the rivers, and launch and supply his successful campaigns south. Cairo has the lowest elevation of any location in Illinois and is the only Illinois city to be surrounded by levees. It is in the area of Southern Illinois known as Little Egypt, for which the city is named after Egypt's capital. Several blocks in the town comprise the Cairo Historic District, listed on the National Register of Historic Places (NRHP). The Old Customs House is also on the NRHP. The city is part of the Cape Girardeau–Jackson, MO–IL Metropolitan Statistical Area. Developed as a river port, Cairo was later bypassed by transportation changes away from the large expanse of low-lying land and water, which surrounds Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Army Corps Of Engineers
, colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = LTG Scott A. Spellmon , commander1_label = Chief of Engineers and Commanding General of the U.S. Army Corps of Engineers , commander2 = MGbr>Richard J. Heitkamp, commander2_label = Deputy Chief of Engineers and Deputy Commanding General , commander3 = MGKimberly M. Colloton, commander3_label = Deputy Commanding General for Military and International Operations , commander4 = MGbr>William H. Graham, commander4_label = Deputy Commanding General for Civil and Emergency Operations , commander5 = COLbr>James J. Handura, commander5_label = Chief of Staff for the U.S. Army Corps of Engi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandbag
A sandbag or dirtbag is a bag or sack made of hessian (burlap), polypropylene or other sturdy materials that is filled with sand or soil and used for such purposes as flood control, military fortification in trenches and bunkers, shielding glass windows in war zones, ballast, counterweight, and in other applications requiring mobile fortification, such as adding improvised additional protection to armored vehicles or tanks. The advantages are that the bags and sand are inexpensive. When empty, the bags are compact and lightweight for easy storage and transportation. They can be brought to a site empty and filled with local sand or soil. Disadvantages are that filling bags is labor-intensive. Without proper training, sandbag walls can be constructed improperly causing them to fail at a lower height than expected, when used in flood-control purposes. They can degrade prematurely in the sun and elements once deployed. They can also become contaminated by sewage in flood waters ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Erosion
Internal erosion is the formation of voids within a soil caused by the removal of material by seepage. It is the second most common cause of failure in levees and one of the leading causes of failures in earth dams, responsible for about half of embankment dam failures. Internal erosion occurs when the hydraulic forces exerted by water seeping through the pores and cracks of the material in the dam and/or foundation are sufficient to detach particles and transport them out of the dam structure. Internal erosion is especially dangerous because there may be no external evidence, or only subtle evidence, that it is taking place. Usually a sand boil can be found, but the boil might be hidden under water. A dam may breach within a few hours after evidence of internal erosion becomes obvious. Piping is a related phenomenon and is defined as the progressive development of internal erosion by seepage, appearing downstream as a hole discharging water. Piping is induced by regressive erosio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (construction)
A levee (), dike ( American English), dyke ( Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastlines. The purpose of a levee is to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. Levees can be naturally occurring ridge structures that form next to the bank of a river, or be an artificially constructed fill or wall that regulates water levels. Ancient civilizations in the Indus Valley, ancient Egypt, Mesopotamia and China all built levees. Today, levees can be found around the world, and failures of levees due to erosion or other causes can be major disasters. Etymology Speakers of American English (notably in the Midwest and Deep South) use the word ''levee'', from the French word (from the feminine past participle of the French verb , 'to raise'). It ori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levee
A levee (), dike (American English), dyke (English in the Commonwealth of Nations, Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually soil, earthen and that often runs parallel (geometry), parallel to the course of a river in its floodplain or along low-lying coastlines. The purpose of a levee is to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. Levees can be naturally occurring ridge structures that form next to the bank of a river, or be an artificially constructed fill dirt, fill or wall that regulates water levels. Ancient civilizations in the Indus Valley civilisation, Indus Valley, ancient Egypt, Mesopotamia and China all built levees. Today, levees can be found around the world, and failures of levees due to erosion or other causes can be major disasters. Etymology Speakers of American English (notably in the Midwestern United States, Midwest and Deep South) u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
