A lahar is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano along a river valley. Lahars are destructive: they can flow tens of metres per second, they have been known to be up to 140 metres deep, large flows tend to destroy any structures in their path, they have been known to decimate entire settlements. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the latter of which killed thousands of people and caused extensive damage to infrastructure; the word lahar is of Javanese origin. The geological term was introduced by Berend George Escher in 1922. A lahar is a volcanic debris flow. Lahars have the consistency and approximate density of wet concrete: fluid when moving, solid at rest. Lahars can be huge; the Osceola Lahar produced by Mount Rainier some 5600 years ago resulted in a wall of mud 140 metres deep in the White River canyon, which covered an area of over 330 square kilometres, for a total volume of 2.3 cubic kilometres.
A lahar of sufficient size and intensity can erase any structure in its path, is capable of carving its own pathway, making the prediction of its course difficult. Conversely, a lahar loses force when it leaves the channel of its flow: frail huts may remain standing, while at the same time being buried to the roof line in mud. A lahar's viscosity decreases with time, can be further thinned by rain, but it solidifies when coming to a stop. Lahars vary in speed. Small lahars less than a few metres wide and several centimetres deep may flow a few metres per second. Large lahars hundreds of metres wide and tens of metres deep can flow several tens of metres per second: much too fast for people to outrun. With the potential to flow at speeds up to 100 kilometres per hour, flow distances of more than 300 kilometres, a lahar can cause catastrophic destruction in its path. Lahars from the 1985 Nevado del Ruiz eruption in Colombia caused the Armero tragedy, which killed an estimated 23,000 people, when the city of Armero was buried under 5 metres of mud and debris.
A lahar caused New Zealand's Tangiwai disaster, where 151 people died after a Christmas Eve express train fell into the Whangaehu River in 1953. Lahars have been responsible for 17% of volcano-related deaths between 1783 and 1997. A lahar can cause fatalities years after its precipitating eruption. For example, the Cabalantian tragedy occurred four years subsequent to the 1991 eruption of Mount Pinatubo. Lahars have several possible causes: Snow and glaciers can be melted by lava and/or pyroclastic surges during an eruption. Lava gushes out of open vents and can mix with wet soil, mud and/or snow on the slope of the volcano making a viscous, high energy lahar. A flood caused by a glacier, lake breakout, or heavy rainfalls can generate lahars called glacier run or jökulhlaup Water from a crater lake, combined with volcanic elements in an eruption. Heavy rainfall on unconsolidated pyroclastic deposits. Volcanic landslides with water. In particular, although lahars are associated with the effects of volcanic activity, lahars can occur without any current volcanic activity, as long as the conditions are right to cause the collapse and movement of mud originating from existing volcanic ash deposits.
Snow and glaciers can melt during periods of mild to hot weather. Earthquakes underneath or close to the volcano can shake material loose and cause it to collapse, triggering a lahar avalanche. Rainfall can cause the still-hanging slabs of solidified mud to come rushing down the slopes at a speed of more than 30 kilometres per hour, causing devastating results. Several mountains in the world, including Mount Rainier in the United States, Mount Ruapehu in New Zealand and Galunggung in Indonesia, are considered dangerous due to the risk of lahars. Several towns in the Puyallup River valley in Washington state, including Orting, are built on top of lahar deposits that are only about 500 years old. Lahars are predicted to flow through the valley every 500 to 1,000 years, so Orting, Puyallup and the Port of Tacoma face considerable risk; the USGS has set up lahar warning sirens in Pierce County, Washington, so that people can flee an approaching debris flow in the event of a Mount Rainier eruption.
A lahar warning system has been set up at Mount Ruapehu by the New Zealand Department of Conservation and hailed as a success after it alerted officials to an impending lahar on 18 March 2007. Since mid-June 1991, when violent eruptions triggered Mount Pinatubo's first lahars in 500 years, a system to monitor and warn of lahars has been in operation. Radio-telemetered rain gauges provide data on rainfall in lahar source regions, acoustic flow monitors on stream banks detect ground vibration as lahars pass, manned watchpoints further confirm that lahars are rushing down Pinatubo's slopes; this system has enabled warnings to be sounded for most but not all major lahars at Pinatubo, saving hundreds of lives. Physical preventative measures by the Philippine government were not adequate to stop over 20 feet of mud from flooding many villages around Mount Pinatubo from 1992 through 1998. Scientists and governments try to identify areas with a high risk of lahars based on historical events and computer models.
Volcano scientists play a critical role in effective hazard education by informing officials and the public about realistic hazard probabilities and
This article is for the volcanic arc. For the namesake mountain range see Cascade Range; the Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles. The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River, the northward limit of the Cascade Range proper; some of the major cities along the length of the arc include Portland and Vancouver, the population in the region exceeds 10 million. All could be affected by volcanic activity and great subduction-zone earthquakes along the arc; because the population of the Pacific Northwest is increasing, the Cascade volcanoes are some of the most dangerous, due to their eruptive history and potential for future eruptions, because they are underlain by weak, hydrothermally altered volcanic rocks that are susceptible to failure.
Mount Rainier is one of the Decade Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior as being worthy of particular study, due to the danger it poses to Seattle and Tacoma. Many large, long-runout landslides originating on Cascade volcanoes have engulfed valleys tens of kilometers from their sources, some of the areas affected now support large populations; the Cascade Volcanoes are part of the Pacific Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. The Cascade Volcanoes have erupted several times in recorded history. Two most recent were Lassen Peak in 1914 to 1921 and a major eruption of Mount St. Helens in 1980, it is the site of Canada's most recent major eruption about 2,350 years ago at the Mount Meager massif. The Cascade Arc includes nearly 20 major volcanoes, among a total of over 4,000 separate volcanic vents including numerous stratovolcanoes, shield volcanoes, lava domes, cinder cones, along with a few isolated examples of rarer volcanic forms such as tuyas.
Volcanism in the arc began about 37 million years ago. Twelve volcanoes in the arc are over 10,000 feet in elevation, the two highest, Mount Rainier and Mount Shasta, exceed 14,000 feet. By volume, the two largest Cascade volcanoes are the broad shields of Medicine Lake Volcano and Newberry Volcano, which are about 145 cubic miles and 108 cubic miles respectively. Glacier Peak is the only Cascade volcano, made of dacite. Over the last 37 million years, the Cascade Arc has been erupting a chain of volcanoes along the Pacific Northwest. Several of the volcanoes in the arc are active; the volcanoes of the Cascade Arc share some general characteristics, but each has its own unique geological traits and history. Lassen Peak in California, which last erupted in 1917, is the southernmost active volcano in the arc, while the Mount Meager massif in British Columbia, which erupted about 2,350 years ago, is considered the northernmost member of the arc. A few isolated volcanic centers northwest of the Mount Meager massif such as the Silverthrone Caldera, a circular 20 km wide dissected caldera complex, may be the product of Cascadia subduction because the igneous rocks andesite, basaltic andesite and rhyolite can be found at these volcanoes as they are elsewhere along the subduction zone.
At issue are the current estimates of plate configuration and rate of subduction, but based on the chemistry of these volcanoes, they are subduction related and therefore part of the Cascade Volcanic Arc. The Cascade Volcanic Arc appears to be segmented. Lavas representing the earliest stage in the development of the Cascade Volcanic Arc crop out south of the North Cascades proper, where uplift of the Cascade Range has been less, a thicker blanket of Cascade Arc volcanic rocks has been preserved. In the North Cascades, geologists have not yet identified with any certainty any volcanic rocks as old as 35 million years, but remnants of the ancient arc's internal plumbing system persist in the form of plutons, which are the crystallized magma chambers that once fed the early Cascade volcanoes; the greatest mass of exposed Cascade Arc plumbing is the Chilliwack batholith, which makes up much of the northern part of North Cascades National Park and adjacent parts of British Columbia beyond. Individual plutons range in age from about 35 million years old to 2.5 million years old.
The older rocks invaded by all this magma were affected by the heat. Around the plutons of the batholith, the older rocks recrystallized; this contact metamorphism produced a fine mesh of interlocking crystals in the old rocks strengthening them and making them more resistant to erosion. Where the recrystallization was intense, the rocks took on a new appearance dark and hard. Many rugged peaks in the North Cascades owe their prominence to this baking; the rocks holding up many such North Cascade giants, as Mount Shuksan, Mount Redoubt, Mount Challenger, Mount Hozomeen, are all recrystallized by plutons of the nearby and underlying Chilliwack batholith. The Garibaldi Volcanic Belt is the northern extension of the Cascade Arc. Volcanoes within the volcanic belt are stratovolcanoes along with the
A pyroclastic flow is a fast-moving current of hot gas and volcanic matter that moves away from a volcano about 100 km/h on average but is capable of reaching speeds up to 700 km/h. The gases can reach temperatures of about 1,000 °C. Pyroclastic flows are a devastating result of certain explosive eruptions, their speed depends upon the density of the current, the volcanic output rate, the gradient of the slope. The word pyroclast is derived from the Greek πῦρ, meaning "fire", κλαστός, meaning "broken in pieces". A name for pyroclastic flows which glow red in the dark is nuée ardente. Pyroclastic flows that contain a much higher proportion of gas to rock are known as "fully dilute pyroclastic density currents" or pyroclastic surges; the lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills and seas. They may contain steam and rock at less than 250 °C. Cold pyroclastic surges can occur when the eruption is from a vent under the sea. Fronts of some pyroclastic density currents are dilute.
A pyroclastic flow is a type of gravity current. There are several mechanisms that can produce a pyroclastic flow: Fountain collapse of an eruption column from a Plinian eruption. In such an eruption, the material forcefully ejected from the vent heats the surrounding air and the turbulent mixture rises, through convection, for many kilometers. If the erupted jet is unable to heat the surrounding air sufficiently, convection currents will not be strong enough to carry the plume upwards and it falls, flowing down the flanks of the volcano. Fountain collapse of an eruption column associated with a Vulcanian eruption; the gas and projectiles create a cloud, denser than the surrounding air and becomes a pyroclastic flow. Frothing at the mouth of the vent during degassing of the erupted lava; this can lead to the production of a rock called ignimbrite. This occurred during the eruption of Novarupta in 1912. Gravitational collapse of a lava dome or spine, with subsequent avalanches and flows down a steep slope.
The directional blast when part of a volcano explodes. As distance from the volcano increases, this transforms into a gravity-driven current; the volumes range from a few hundred cubic meters to more than 1,000 cubic kilometres. The larger ones can travel for hundreds of kilometres, although none on that scale have occurred for several hundred thousand years. Most pyroclastic flows are around travel for several kilometres. Flows consist of two parts: the basal flow hugs the ground and contains larger, coarse boulders and rock fragments, while an hot ash plume lofts above it because of the turbulence between the flow and the overlying air and heating cold atmospheric air causing expansion and convection; the kinetic energy of the moving cloud will flatten buildings in its path. The hot gases and high speed make them lethal, as they will incinerate living organisms instantaneously: The cities of Pompeii and Herculaneum, for example, were engulfed by pyroclastic surges on August 24, 79 AD with many lives lost.
The 1902 eruption of Mount Pelée destroyed the Martinique town of St. Pierre. Despite signs of impending eruption, the government deemed St. Pierre safe due to hills and valleys between it and the volcano, but the pyroclastic flow charred the entirety of the city, killing all but two of its 30,000 residents. A pyroclastic surge killed volcanologists Harry Glicken and Katia and Maurice Krafft and 40 other people on Mount Unzen, in Japan, on June 3, 1991; the surge started as a pyroclastic flow and the more energised surge climbed a spur on which the Kraffts and the others were standing. On 25 June, 1997 a pyroclastic flow travelled down Mosquito Ghaut on the Caribbean island of Montserrat. A large energized pyroclastic surge developed; this flow could not be restrained by the Ghaut and spilled out of it, killing 19 people who were in the Streatham village area. Several others in the area suffered severe burns. Testimonial evidence from the 1883 eruption of Krakatoa, supported by experimental evidence, shows that pyroclastic flows can cross significant bodies of water.
However, that might be a pyroclastic surge, not flow, because the density of a gravity current means it cannot move across the surface of water. One flow reached the Sumatran coast as much as 48 km away. A 2006 BBC documentary film, Ten Things You Didn't Know About Volcanoes, demonstrated tests by a research team at Kiel University, Germany, of pyroclastic flows moving over water; when the reconstructed pyroclastic flow hit the water, two things happened
White Chuck Cinder Cone
White Chuck Cinder Cone is a cinder cone near Glacier Peak in Snohomish County of Washington, USA. It was first discovered in 1934 and its elevation is 6,020 feet. Based on the amount of glacial erosion on the cinder cone, it is between 2,000 and 17,000 years old
New Westminster is a city in the Lower Mainland region of British Columbia, a member municipality of Metro Vancouver. It was founded by Major-General Richard Moody as the capital of the new-born Colony of British Columbia in 1858, continued in that role until the Mainland and Island Colonies were merged in 1866, was the Mainland's largest city from that year until it was passed in population by Vancouver during the first decade of the 20th Century, it is located on the banks of the Fraser River as it turns southwest towards its estuary, on the southwest side of the Burrard Peninsula and at the centre of the Greater Vancouver region. Before the settlers arrived from various parts of the world, the area now known as New Westminster was inhabited by Qayqayt First Nation; the discovery of gold in B. C. and the arrival of gold seekers from the south prompted fear amongst the settlers that Americans may invade to take over this land. Richard Clement Moody arrived in British Columbia in December 1858, at the head of the Royal Engineers, Columbia Detachment, having been hand picked to “found a second England on the shores of the Pacific”.
Moody ‘wanted to build a city of beauty in the wilderness’ and planned his city as an iconic visual metaphor for British dominance, ‘styled and located with the objective of reinforcing the authority of the Crown and of the robe’. Subsequent to the enactment of the Pre-emption Act of 1860, Moody settled the Lower Mainland and selected the site and founded the new capital, New Westminster. Moody and the Royal Engineers were trained in settlement and selected the site because of its defensibility: it was farther from the American border than the site of the colony's proclamation, Fort Langley, possessed "great facilities for communication by water, as well as by future great trunk railways into the interior", possessed an excellent port. Moody was struck by the majestic beauty of the site, writing in his letter to Blackwood, "The entrance to the Frazer is striking--Extending miles to the right & left are low marsh lands & yet fr the Background of Superb Mountains-- Swiss in outline, dark in woods, grandly towering into the clouds there is a sublimity that impresses you.
Everything is large and magnificent, worthy of the entrance to the Queen of England’s dominions on the Pacific mainland. My imagination converted the silent marshes into Cuyp-like pictures of horses and cattle lazily fattening in rich meadows in a glowing sunset; the water of the deep clear Frazer was of a glassy stillness, not a ripple before us, except when a fish rose to the surface or broods of wild ducks fluttered away". It was suggested by Moody and the Royal Engineers, Columbia Detachment that the site be proclaimed "Queensborough". Governor James Douglas proclaimed the new capital with this name on February 14, 1859; the name "Queensborough", did not appeal to London and it was Queen Victoria who named the city after Westminster, that part of the British capital of London where the Parliament Buildings were, are to this day, situated. From this naming by the Queen, the City gained its official nickname, "The Royal City". A year New Westminster became the first City in British Columbia to be incorporated and have an elected municipal government.
It became a major outfitting point for prospectors coming to the Fraser Gold Rush, as all travel to the goldfield ports of Yale and Port Douglas was by steamboat or canoe up the Fraser River. However, Colonial Office Secretary Sir Edward Bulwer-Lytton'forgot the practicalities of paying for clearing and developing the site and the town’ and the efforts of Moody's Engineers were continuously hampered by insufficient funds, together with the continuous opposition of Douglas,'made it impossible for design to be fulfilled’. Governor Douglas had little affection for the city. In contrast to Victoria, where settlers from England had established a strong British presence, New Westminster's early citizens were Canadians and Maritimers, who brought a more business-oriented approach to commerce and dismissed the pretensions of the older community. Despite being granted a municipal council, the mainlanders in New Westminster pressed for a legislative assembly to be created for British Columbia, were infuriated when Governor Douglas granted free port status to Victoria, which stifled the economic growth of the Fraser River city.
Moreover, to pay for the expense of building roads into the Interior of the colony, Douglas imposed duties on imports into New Westminster. In 1866, the colony of British Columbia and the colony of Vancouver Island were united as "British Columbia". However, the capital of the Colony of Vancouver Island, located on the southern tip of Vancouver Island, was made the capital of the newly amalgamated Colony of British Columbia, following a vote in the House of Assembly. On the day of the vote one member of the assembly, William Cox, shuffled the pages of the speech that William Franklyn from Nanaimo intended to give, so that Franklyn lost his place and read the first paragraph three times. Cox popped the lenses of Franklyn's glasses from their frames so that the Nanaimo representative could see nothing at all of his speech. After a recess to settle the resulting uproar and allow the member from Nanaimo a chance to sort out his speaking notes and his spectacles, on the members' return to the House of Assembly, the Sp
A stratovolcano known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas; the lava flowing from stratovolcanoes cools and hardens before spreading far, due to high viscosity. The magma forming this lava is felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows have travelled as far as 15 km. Stratovolcanoes are sometimes called "composite volcanoes" because of their composite stratified structure built up from sequential outpourings of erupted materials, they are in contrast to the less common shield volcanoes. Two famous examples of stratovolcanoes are Krakatoa, known for its catastrophic eruption in 1883 and Vesuvius, whose eruption in AD79 caused destruction of Pompeii and Herculaneum in 79 AD.
Both eruptions claimed thousands of lives. In modern times, Mount St. Helens and Mount Pinatubo have erupted catastrophically, with lesser losses of lives; the possible existence of stratovolcanoes on other terrestrial bodies of the Solar System has not been conclusively demonstrated. The one feasible exception are the existence of some isolated massifs on Mars, for example the Zephyria Tholus. Stratovolcanoes are common at subduction zones, forming chains and clusters along plate tectonic boundaries where oceanic crust is drawn under continental crust or another oceanic plate; the magma forming stratovolcanoes rises when water trapped both in hydrated minerals and in the porous basalt rock of the upper oceanic crust is released into mantle rock of the asthenosphere above the sinking oceanic slab. The release of water from hydrated minerals is termed "dewatering", occurs at specific pressures and temperatures for each mineral, as the plate descends to greater depths; the water freed from the rock lowers the melting point of the overlying mantle rock, which undergoes partial melting and rises due to its lighter density relative to the surrounding mantle rock, pools temporarily at the base of the lithosphere.
The magma rises through the crust, incorporating silica-rich crustal rock, leading to a final intermediate composition. When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. There, the low pressure allows water and other volatiles dissolved in the magma to escape from solution, as occurs when a bottle of carbonated water is opened, releasing CO2. Once a critical volume of magma and gas accumulates, the plug of the volcanic vent is broken, leading to a sudden explosive eruption. In recorded history, explosive eruptions at subduction zone volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo erupt with explosive force: the magma is too stiff to allow easy escape of volcanic gases; as a consequence, the tremendous internal pressures of the trapped volcanic gases remain and intermingle in the pasty magma. Following the breaching of the vent and the opening of the crater, the magma degasses explosively.
The magma and gases blast out with full force. Since 1600 CE, nearly 300,000 people have been killed by volcanic eruptions. Most deaths were caused by pyroclastic flows and lahars, deadly hazards that accompany explosive eruptions of subduction-zone stratovolcanoes. Pyroclastic flows are swift, avalanche-like, ground-sweeping, incandescent mixtures of hot volcanic debris, fine ash, fragmented lava and superheated gases that can travel at speeds in excess of 160 km/h. Around 30,000 people were killed by pyroclastic flows during the 1902 eruption of Mount Pelée on the island of Martinique in the Caribbean. In March to April 1982, three explosive eruptions of El Chichón in the State of Chiapas in southeastern Mexico, caused the worst volcanic disaster in that country's history. Villages within 8 km of the volcano were destroyed by pyroclastic flows, killing more than 2,000 people. Two Decade Volcanoes that erupted in 1991 provide examples of stratovolcano hazards. On June 15, Mount Pinatubo spewed an ash cloud 40 km into the air and produced huge pyroclastic surges and lahar floods that devastated a large area around the volcano.
Pinatubo, located in Central Luzon just 90 km west-northwest from Manila, had been dormant for 6 centuries before the 1991 eruption, which ranks as one of the largest eruptions in the 20th century. In 1991, Japan's Unzen Volcano, located on the island of Kyushu about 40 km east of Nagasaki, awakened from its 200-year slumber to produce a new lava dome at its summit. Beginning in June, repeated collapse of this erupting dome generated ash flows that swept down the mountain's slopes at speeds as high as 200 km/h. Unzen is one of more than 75 active volcanoes in Japan; the eruption of Mount Vesuvius in 79 smothered the nearby ancient cities of Pompeii and Herculaneum with thick deposits of pyroclastic surges and lava flows. Although death toll is estimated between 13,000 and 26,000 remains, the exact number still remains unknown. Vesuvius is recognized as one of the most dangerous volcanoes, due to its
Seattle is a seaport city on the West Coast of the United States. It is the seat of Washington. With an estimated 730,000 residents as of 2018, Seattle is the largest city in both the state of Washington and the Pacific Northwest region of North America. According to U. S. Census data released in 2018, the Seattle metropolitan area’s population stands at 3.87 million, ranks as the 15th largest in the United States. In July 2013, it was the fastest-growing major city in the United States and remained in the Top 5 in May 2015 with an annual growth rate of 2.1%. In July 2016, Seattle was again the fastest-growing major U. S. city, with a 3.1% annual growth rate. Seattle is the northernmost large city in the United States; the city is situated on an isthmus between Puget Sound and Lake Washington, about 100 miles south of the Canada–United States border. A major gateway for trade with Asia, Seattle is the fourth-largest port in North America in terms of container handling as of 2015; the Seattle area was inhabited by Native Americans for at least 4,000 years before the first permanent European settlers.
Arthur A. Denny and his group of travelers, subsequently known as the Denny Party, arrived from Illinois via Portland, Oregon, on the schooner Exact at Alki Point on November 13, 1851; the settlement was moved to the eastern shore of Elliott Bay and named "Seattle" in 1852, in honor of Chief Si'ahl of the local Duwamish and Suquamish tribes. Today, Seattle has high populations of Native, Scandinavian and Asian Americans, as well as a thriving LGBT community that ranks 6th in the United States for population. Logging was Seattle's first major industry, but by the late 19th century, the city had become a commercial and shipbuilding center as a gateway to Alaska during the Klondike Gold Rush. Growth after World War II was due to the local Boeing company, which established Seattle as a center for aircraft manufacturing; the Seattle area developed into a technology center from the 1980s onwards with companies like Microsoft becoming established in the region. Internet retailer Amazon was founded in Seattle in 1994, major airline Alaska Airlines is based in SeaTac, serving Seattle's international airport, Seattle–Tacoma International Airport.
The stream of new software and Internet companies led to an economic revival, which increased the city's population by 50,000 between 1990 and 2000. Owing to its increasing population in the 21st century and the state of Washington have some of the highest minimum wages in the country, at $15 per hour for smaller businesses and $16 for the city's largest employers. Seattle has a noteworthy musical history. From 1918 to 1951, nearly two dozen jazz nightclubs existed along Jackson Street, from the current Chinatown/International District to the Central District; the jazz scene nurtured the early careers of Ray Charles, Quincy Jones, Ernestine Anderson, others. Seattle is the birthplace of rock musician Jimi Hendrix, as well as the origin of the bands Nirvana, Pearl Jam, Alice in Chains, Foo Fighters and the alternative rock movement grunge. Archaeological excavations suggest that Native Americans have inhabited the Seattle area for at least 4,000 years. By the time the first European settlers arrived, the people occupied at least seventeen villages in the areas around Elliott Bay.
The first European to visit the Seattle area was George Vancouver, in May 1792 during his 1791–95 expedition to chart the Pacific Northwest. In 1851, a large party led by Luther Collins made a location on land at the mouth of the Duwamish River. Thirteen days members of the Collins Party on the way to their claim passed three scouts of the Denny Party. Members of the Denny Party claimed land on Alki Point on September 28, 1851; the rest of the Denny Party set sail from Portland and landed on Alki point during a rainstorm on November 13, 1851. After a difficult winter, most of the Denny Party relocated across Elliott Bay and claimed land a second time at the site of present-day Pioneer Square, naming this new settlement Duwamps. Charles Terry and John Low remained at the original landing location and reestablished their old land claim and called it "New York", but renamed "New York Alki" in April 1853, from a Chinook word meaning "by and by" or "someday". For the next few years, New York Alki and Duwamps competed for dominance, but in time Alki was abandoned and its residents moved across the bay to join the rest of the settlers.
David Swinson "Doc" Maynard, one of the founders of Duwamps, was the primary advocate to name the settlement after Chief Seattle of the Duwamish and Suquamish tribes. The name "Seattle" appears on official Washington Territory papers dated May 23, 1853, when the first plats for the village were filed. In 1855, nominal land settlements were established. On January 14, 1865, the Legislature of Territorial Washington incorporated the Town of Seattle with a board of trustees managing the city; the Town of Seattle was disincorporated on January 18, 1867, remained a mere precinct of King County until late 1869, when a new petition was filed and the city was re-incorporated December 2, 1869, with a mayor–council government. The corporate seal of the City of Seattle carries the date "1869" and a likeness of Chief Sealth in left profile. Seattle has a history of boom-and-bust cycles, like many other cities near areas of extensive natural and mineral resources. Seattle has risen several times economically gone into precipitous decline, but it has used those periods to rebuild solid infrastructure