132-562: The Mount Edziza volcanic complex ( / ə d ˈ z aɪ z ə / əd-zy-zə ; abbreviated MEVC ) is a group of volcanoes and associated lava flows in northwestern British Columbia , Canada. Located on the Tahltan Highland , it is 40 kilometres (25 miles) southeast of Telegraph Creek and 85 kilometres (53 miles) southwest of Dease Lake . The complex encompasses a broad, steep-sided lava plateau that extends over 1,000 square kilometres (390 square miles). Its highest summit
264-609: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Volcanologist A volcanologist , or volcano scientist , is a geologist who focuses on understanding the formation and eruptive activity of volcanoes . Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions , collect eruptive products including tephra (such as ash or pumice ), rock and lava samples. One major focus of inquiry in recent times
396-484: A magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas
528-711: A broad east–west valley separating the Spectrum Range in the south from the Mount Edziza area in the north. The eastern side of the MEVC is flanked by Mowdade Lake, Kakiddi Lake , Mowchilla Lake and Nuttlude Lake in Kakiddi Valley; the last three drain north into the Klastline River . Buckley Lake is the main lake bordering the northern side of the MEVC while Mess Lake is the main lake bordering
660-506: A broad valley paralleling the MEVC. It then flows northwest into the Stikine River near the community of Telegraph Creek . Several short tributaries of Mess Creek drain the western half of the MEVC where they have cut steep-sided canyons into the volcanic plateau. This includes Crayke Creek which flows to the southwest, Elwyn Creek which flows to the west, Kitsu Creek which flows to the northwest, Raspberry Creek which flows to
792-640: A canyon west of the Armadillo Highlands and also contains only one named tributary, Flyin Creek , which flows northwest from near the west side of Cache Hill . The only named tributary of Taweh Creek is Sezill Creek which flows northwest in a canyon southwest of Mount Edziza. To the east, the MEVC overlooks a drainage divide that lies in a broad hummocky lowland. Its upper eastern half is drained by tributaries of Kakiddi Creek. This includes Nido Creek , Tenchen Creek and Tennaya Creek which flow to
924-1009: A few hundred years ago. The cause of volcanic activity in the Northern Cordilleran Volcanic Province is thought to be due to rifting of the North American Cordillera driven by changes in relative plate motion between the North American and Pacific plates. The MEVC is part of a subdivision of the NCVP called the Stikine Subprovince. This subprovince, confined to the Stikine region of northwestern British Columbia, includes three other volcanic complexes: Heart Peaks , Hoodoo Mountain and Level Mountain . The four complexes differ petrologically and/or volumetrically from
1056-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,
1188-489: A long and narrow graben -like depression possibly linked to volcanism of the volcanic complex . The eastern edge of the valley is bounded by north-trending faults , one of which has been traced for more than 24 kilometres (15 miles). This fault shows signs of having been active contemporaneously with volcanism of the MEVC; it has vertically displaced Holocene basalt flows by 15 to 20 metres (50 to 70 feet) and older basalt flows by 91 to 122 metres (299 to 400 feet), such that
1320-554: A nearly circular, more than 10-kilometre-wide (6.2-mile) dome with a thickness of up to 650 metres (2,130 feet). Armadillo Peak represents the eroded remains of a small caldera whose 2,194-metre (7,198-foot) summit is capped by a 180-metre-thick (590-foot) sequence of ponded lava flows. Various stages of erosion have modified these central volcanoes; in some cases, only a few small remnants of their original surface remain. The degree of erosion becomes less pronounced on those that have more recently formed. Several cinder cones dotting
1452-516: A nearly continuous record of activity dating from the Miocene . It covers 1,000 square kilometres (390 square miles) and comprises 665 cubic kilometres (160 cubic miles) of volcanic material, making it the second largest eruptive centre in the NCVP after Level Mountain. The MEVC is also the second most long-lived eruptive centre in the NCVP after Level Mountain, having started erupting at least 7.4 million years ago. The eruption sequence and style of
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#17327838236771584-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano
1716-646: A possibility at any time of the year. The closest weather stations to the MEVC are located at Telegraph Creek and Dease Lake , which lie about 40 kilometres (25 miles) to the northwest and 85 kilometres (53 miles) to the northeast, respectively. Meteorological data from the Telegraph Creek and Dease Lake weather stations suggest that the MEVC area has a temperature gradient of around −1.5 degrees Celsius (29.3 degrees Fahrenheit) per 1,000-metre (3,300-foot) increase in elevation. The data also suggest that precipitation likely increases with altitude. At Mess Creek,
1848-610: A potential hazard as they have formerly dammed the Klastline and Stikine rivers, the latter of which contains a major salmon fishery. Another potential hazard at the MEVC is the ignition of wildfires by eruptions as the surrounding area has vegetation. An eruption under the ice cap would possibly produce floods or lahars that could flow into the Stikine or Iskut rivers, potentially destroying salmon runs and threatening river bank villages. Like other volcanic complexes in Canada,
1980-418: A study of aenigmatite crystals which occur in peralkaline rocks of the MEVC. Yagi Ridge in the Spectrum Range was named in honour of Kenzō Yagi who traversed this ridge with Souther during their geological studies. During his last year of serious field work in 1992, Souther published an extensive bulletin on his work entitled The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia which highlighted
2112-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa
2244-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on
2376-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while
2508-548: A warning for a large eruption; the system might detect activity only once the complex has started erupting. If the MEVC were to erupt, mechanisms exist to orchestrate relief efforts. The Interagency Volcanic Event Notification Plan was created to outline the notification procedure of some of the main agencies that would respond to an erupting volcano in Canada, an eruption close to the Canada–United States border or any eruption that would affect Canada. The MEVC lies within
2640-399: Is Obsidian Ridge , a mountain ridge containing high-quality obsidian . Destell Pass is a narrow rock cleft northwest of Artifact Ridge that provides access between the broad upland valleys of Artifact Creek and Raspberry Creek . It is one of two named mountain passes in the MEVC, the other being Raspberry Pass between the heads of Bourgeaux Creek and Raspberry Creek. Raspberry Pass is
2772-427: Is 2,786 metres (9,140 feet) in elevation, making the MEVC the highest of four large complexes in an extensive north–south trending volcanic region. It is obscured by an ice cap characterized by several outlet glaciers that stretch out to lower altitudes. The MEVC consists of several types of volcanoes , including stratovolcanoes , shield volcanoes , cinder cones and lava domes . These volcanoes have formed over
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#17327838236772904-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in
3036-486: Is an isolated, flat-topped hill with steep sides called Gnu Butte . The Mess Creek Escarpment is a long, often cliff-like feature forming the western edge of the MEVC. It runs along the eastern side of Mess Creek and exposes thick, flat-lying lava flows. Artifact Ridge is a crescent-shaped mountain ridge east of the Kitsu Plateau and just north of Artifact Creek . Just south of Artifact Ridge and Artifact Creek
3168-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where
3300-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in
3432-483: Is drained by many outlet glaciers that spread in broad lobes onto the Big Raven Plateau whereas the eastern side is drained by distributary glaciers that drape down steep slopes to form discontinuous icefalls . Five officially named glaciers are situated at the northern and southern ends of the MEVC. Idiji Glacier lies southeast of Mount Edziza on the eastern side of the MEVC. At the head of Nagha Creek in
3564-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for
3696-513: Is one of seven ecosections comprising the Boreal Mountains and Plateaus Ecoregion , a large ecological region of northwestern British Columbia encompassing high plateaus and rugged mountains with intervening lowlands . Boreal forests of black and white spruce occur in the lowlands and valley bottoms of this ecoregion whereas birch , spruce and willow form forests on the mid-slopes. Extensive alpine altai fescue covers
3828-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near
3960-556: Is the prediction of eruptions to alleviate the impact on surrounding populations and monitor natural hazards associated with volcanic activity. Geologists who research volcanic materials that make up the solid Earth are referred to as igneous petrologists. The word volcanologist (or vulcanologist ) is derived from the English volcanology ( volcano + -logy ), which was derived from the French volcanologie (or vulcanologie), which
4092-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in
Mount Edziza volcanic complex - Misplaced Pages Continue
4224-427: Is volcanically dormant but it still remains hydrothermally active. Four hot spring areas are found along the western flank of the MEVC at Mess Lake, Mess Creek, Elwyn Creek and Sezill Creek, the latter three of which have recorded water temperatures of 42.5 degrees Celsius (108.5 degrees Fahrenheit), 36 degrees Celsius (97 degrees Fahrenheit) and 46 degrees Celsius (115 degrees Fahrenheit), respectively. Discharge at
4356-560: The British Columbia Coast , making Edziza obsidian the most widely distributed obsidian in western North America. Edziza obsidian from the Hidden Falls archaeological site in Alaska has yielded a hydration date of 10,000 years; this suggests the MEVC was being exploited as an obsidian source soon after ice sheets of the last glacial period retreated. The MEVC continues to be an important cultural resource for
4488-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off
4620-626: The Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,
4752-674: The Iskut River . A northerly-trending, elliptical, composite shield volcano consisting of multiple flat-lying lava flows forms the plateau. The MEVC is surrounded on the east by the Skeena Mountains and the Klastline Plateau while to the west it is flanked by the Coast Mountains . It lies on the eastern edge of the Tahltan Highland , a southeast-trending upland area extending along the western side of
4884-978: The Stikine Plateau . This upland area lies between the Taku River in the north, the Boundary Ranges in the west and the head of the Iskut River in the east. The width of the Tahltan Highland varies from about 8 kilometres (5.0 miles) in the north to about 48 kilometres (30 miles) in the south where the Stikine River crosses the highland . The MEVC is in the Southern Boreal Plateau Ecosection which consists of several upland summits as well as wide river valleys and deeply incised plateaus. It
5016-587: The Tahltan language , referring to the deep volcanic ash deposits or pumice -like sand covering large portions of the Big Raven Plateau around Mount Edziza . According to David Stevenson of University of Victoria 's Anthropology Department, "sand" or "dust" is instead translated as "kutlves" in the Tahltan language. An explanation listed in the BC Parks brochure is that Edziza means "cinders" in
5148-739: The University of Wisconsin–Milwaukee , Ian Spooner of Acadia University , J. Osborn of the University of Calgary , Kirstie Simpson of the Geological Survey of Canada and Bill McIntosh of the New Mexico Institute of Mining and Technology . Five students conducted studies at the MEVC in 2007, namely Chira Endress of Dickinson College, Jeff Hungerford of the University of Pittsburgh, Courtney Haynes of Dickinson College, Alex Floyd of Dickinson College and Kristen LaMoreaux of
5280-499: The Yukon Telegraph Trail for maintenance. One of these maintenance cabins existed at Raspberry Creek in the central portion of the MEVC. The Yukon Telegraph Line and trail were maintained until 1936 when they were abandoned with the advent of radio communication. Remnants of this telegraphy system include collapsed cabins, telegraph wire and a few telegraph poles. The MEVC is one of the best-studied volcanic centres in
5412-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when
Mount Edziza volcanic complex - Misplaced Pages Continue
5544-449: The timberline where grizzly bears are occasionally seen. The alpine and subalpine zones between Mount Edziza and the western escarpment contain small herds of Osborn caribou . The western escarpment, the Spectrum Range and the eastern, western and southern flanks of Mount Edziza contain mountain goats and stone sheep . Other mammals in the area include moose, black bears and wolves . Several species of birds are also present in
5676-512: The Canadian Cordillera. By 1970, Souther and his assistant Maurice Lambert had established that episodic eruptions of alkali basalt and silicic peralkaline lavas had taken place at the MEVC over a timespan of at least 10 million years. They had also established that volcanism of the MEVC was accompanied by east–west extension and incipient rifting of Earth's crust . In 1974, Souther and Japanese volcanologist Kenzō Yagi conducted
5808-615: The Holocene. Several eruptions of the latest magmatic cycle have not been quantitatively dated. Instead, a Holocene age is inferred because their eruptive products do not show evidence of having been glaciated by the Cordilleran Ice Sheet , which retreated from the area about 11,000 years ago. Therefore, many of these inferred Holocene eruptions may have occurred as early as the time of glacial retreat. An eruption recurrence interval of 379 years has been calculated for
5940-492: The MEVC a high threat volcanic complex because it has had the highest eruption rate in Canada throughout the Holocene. However, its extremely remote location makes it less hazardous than volcanoes in southwestern British Columbia. MEVC trachyte and rhyolite have silica-rich compositions that are comparable to those associated with the most powerful eruptions around the world; parts of northwestern Canada could be affected by an ash column if an explosive eruption were to happen at
6072-573: The MEVC a potential high-temperature geothermal resource area but it does not warrant subsurface exploration due to its remote location. The Mess Lake Hot Springs are situated near the southeastern corner of Mess Lake. They lie at an elevation of 760 metres (2,490 feet) and have created massive deposits of tufa that cover more than 120 hectares (300 acres). These springs had a vigorous flow of warm water in 1965, but by 1992 they were discharging water below human body temperature. The Mess Creek Hot Springs 7 kilometres (4.3 miles) south of Mess Lake are on
6204-489: The MEVC are drained by tributaries of the Iskut River. This includes Ball Creek which flows to the south from the southeastern side of the Spectrum Range, More Creek which flows to the southeast from the southern side of the Spectrum Range and the Little Iskut River which flows to the southeast from the southeastern side of the Spectrum Range. The only named tributary of Ball Creek is Chachani Creek which flows to
6336-441: The MEVC are mafic alkali basalts and hawaiites, which comprise about 60% of the volcanic complex. MEVC hawaiites are thought to be the product of partial fractional crystallization and the accumulation of feldspar inside rising columns of mantle -derived alkali basaltic magma. Volcanic rocks of intermediate composition such as benmoreite , trachybasalt , mugearite and tristanite are present in relatively small volumes and are
6468-402: The MEVC by dividing 11,000 years by the number of demonstrable Holocene eruptions, of which there are at least 29. This would make the MEVC the most active eruptive centre in Canada throughout the Holocene. It is also one of the most widespread areas of recent volcanism in Canada. Eruptions have occurred subaqueously , subglacially and subaerially throughout the long eruptive history of
6600-407: The MEVC for thousands of years. Historically, the local Tahltan people used volcanic glass from the MEVC to make tools and weaponry. Intermittent geological work has been carried out at the volcanic complex since at least the 1950s, the most detailed studies having been conducted in the 1960s. A large provincial park , which can only be accessed by aircraft or by a network of footpaths , dominates
6732-459: The MEVC is about 65 kilometres (40 miles) long and 20 kilometres (12 miles) wide. It comprises a broad, steep-sided, intermontane plateau that rises from a base elevation of 760 or 816 metres (2,500 or 2,675 feet). Its sides tower 760 metres (2,500 feet) above adjacent valleys that serve as drainageways for several streams. The edges of the plateau have been deeply incised by creeks that flow eastward and westward into Mess Creek , Kakiddi Creek and
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#17327838236776864-484: The MEVC is not monitored closely enough by the Geological Survey of Canada to ascertain its activity level. The Canadian National Seismograph Network has been established to monitor earthquakes throughout Canada, but it is too far away to provide an accurate indication of activity under the complex. It may sense an increase in seismic activity if the MEVC becomes highly restless, but this may only provide
6996-674: The MEVC is the Stikinia terrane , a Paleozoic and Mesozoic suite of volcanic and sedimentary rocks that accreted to the continental margin of North America during the Jurassic . Rocks of Paleozoic age such as limestone , bedded tuff and volcanic rocks of intermediate composition underlie the western and southern portions of the MEVC. Mesozoic rocks underlie most of the MEVC and include andesite , basaltic andesite , volcanic sandstone , siltstone , shale , greywacke , limestone and chert . The youngest basement rocks are those of
7128-780: The MEVC, along with its chemistry, mineralogy and isotopic composition, is similar to continental peralkaline volcanism at the Rainbow Range of central British Columbia, the Afar Depression of East Africa and parts of the Great Basin of the western United States. Five cycles of magmatic activity created the MEVC; one in the Miocene, one in the Plio-Pleistocene , two in the Pleistocene and one in
7260-783: The MEVC. The Mount Edziza volcanic complex is sometimes referred to as the Mount Edziza–Spectrum Range complex or the Mount Edziza Plateau. Stratigraphically , it has also been referred to as the Mount Edziza Group or the Edziza Group. A number of explanations have been made regarding the origin of the name Edziza. A 1927 report by J. Davidson of the British Columbia Land Surveyors claims that Edziza means "sand" in
7392-479: The MEVC. Ash columns can drift for thousands of kilometres downwind and often become increasingly spread out over a larger area with increasing distance from an erupting vent. The MEVC lies under a major air route from Vancouver , British Columbia to Whitehorse , Yukon, suggesting the volcanic complex poses a potential threat to air traffic. Volcanic ash reduces visibility and can cause jet engine failure, as well as damage to other aircraft systems. Lava flows are also
7524-779: The MEVC. Interactions between ice and volcanism are well-documented at the MEVC, occurring in seven of the 13 geological formations comprising the volcanic complex. This includes the Pyramid, Ice Peak, Pillow Ridge, Edziza, Arctic Lake, Klastline and Big Raven formations which have all formed within the last two million years. Volcano-ice interactions at these formations is represented by pillow lava , tuff breccia , hyaloclastite , glacial till interbedded with lava flows, and massive lava with well-developed slender columnar joints . The MEVC has been scoured by regional glaciations at least twice during its eruptive history, as well as several smaller advances of local alpine glaciers. The MEVC
7656-421: The MEVC. This rapid glacial recession is apparent from the lack of vegetation on the barren, rocky ground between the glaciers and their trim lines which are up to 2 kilometres (1.2 miles) apart. The MEVC has been extensively modified by local and regional glaciations as evidenced by the existence of drumlins and glacial striations , which record ice movement to the north-northwest across the western portion of
7788-609: The NCVP. It was identified by the mapping program of Operation Stikine in 1956 along with Level Mountain, the Iskut-Unuk River Cones and many smaller volcanoes in the Canadian Cordillera . Their identification played a role in the closing of Canada's gap in the Ring of Fire because it allowed them to be added on the world volcanic map. The mapping program of Operation Stikine, masterminded by Jack Souther,
7920-883: The Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which
8052-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like
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#17327838236778184-753: The Sezill Creek, Elwyn Creek and Mess Lake hot springs may be linked to shallow hydrothermal systems driven by residual magmatic heat as they are adjacent to recently active eruptive centres. In contrast, the Mess Creek Hot Springs may be discharging from a deeply circulating hydraulic system along a major fault on the western side of Mess Creek valley. Estimated subsurface temperatures, as derived from geothermometers , are 177 degrees Celsius (351 degrees Fahrenheit) based on silica concentrations and 227 degrees Celsius (441 degrees Fahrenheit) based on sodium - potassium - calcium ratios. This makes
8316-535: The Sloko Group which comprises Early Tertiary intermediate calc-alkaline volcanic rocks and related subvolcanic plutons . These rocks were tilted, cut by normal faults and heavily eroded before volcanism began at the MEVC in the Late Miocene , such that the volcanic complex was built on a mature, gently rolling Tertiary erosion surface . The MEVC lies on the eastern shoulder of Mess Creek valley,
8448-660: The Snowshoe Lava Field covers about 40 square kilometres (15 square miles) at the southern end of the plateau. At the northwestern end of the Spectrum Range is the Kitsu Plateau ; its dominant feature is the even smaller Mess Lake Lava Field which covers 18 square kilometres (6.9 square miles). The Arctic Lake Plateau is the southernmost of the three subplateaus; it consists of a nearly flat upland containing Outcast Hill , Tadekho Hill , Wetalth Ridge , Nahta Cone, Source Hill , Thaw Hill and Exile Hill . In
8580-410: The Spectrum Range and the Armadillo Highlands as part of the neoglaciation . As these glaciers advanced they built up to 18-metre-high (59-foot) terminal moraines on the plateau surface which comprise the trim lines of the current mountain glaciers. The present trend towards a more moderate climate put an end to the neoglacial period in the 19th century, resulting in rapid glacial recession throughout
8712-574: The Spectrum Range in 1988. The MEVC is part of the Northern Cordilleran Volcanic Province (NCVP), a broad area of shield volcanoes, lava domes , cinder cones and stratovolcanoes extending from northwestern British Columbia northwards through Yukon into easternmost Alaska . The dominant rocks comprising these volcanoes are alkali basalts and hawaiites , but nephelinite , basanite and peralkaline phonolite , trachyte and comendite are locally abundant. These rocks were deposited by volcanic eruptions from 20 million years ago to as recently as
8844-467: The Tahltan language. Another explanation proposed by Canadian volcanologist Jack Souther is that Edziza is a corruption of Edzerza, the name of a local Tahltan family. The geomorphology of the MEVC is in some ways similar to that of the Eyjafjallajökull volcano in Iceland. This includes its overall elongated structure, its flanking basaltic lava fields and its summit ice cap surrounded by silica -rich volcanic rocks. The elongated structure of
8976-440: The Tahltan people. In 2021, Chad Norman Day, president of the Tahltan Central Government, said "Mount Edziza and the surrounding area has always been sacred to the Tahltan Nation. The obsidian from this portion of our territory provided us with weaponry, tools and trading goods that ensured our Tahltan people could thrive for thousands of years." Along the western side of the MEVC and through its central portion at Raspberry Pass are
9108-562: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in
9240-446: The University of Pittsburgh. Much of the MEVC was designated as a provincial park in 1972 to showcase its geological and geothermal features. A 101,171-hectare (250,000-acre) recreation area surrounding the 132,000-hectare (330,000-acre) park was also established in 1972. In 1989, Mount Edziza Provincial Park roughly doubled in size when 96,770 hectares (239,100 acres) was annexed from the Mount Edziza Recreation Area . In doing so,
9372-466: The area, including scaup , owls , goldeneye , grebes , gyrfalcons , white-winged scoters , ravens , grouse and ptarmigans . The area between Buckley Lake and Telegraph Creek contains peat meadows , shrub fields and wet grasslands . It is characterized by long, severe winters with short growing seasons and deeply frozen soils. The Mess Creek, Kakiddi and Klastline valleys are intermixed with white spruce, trembling aspen and lodgepole pine ,
9504-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to
9636-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down
9768-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in
9900-599: The extreme northern flank of the MEVC and two unnamed cones in Walkout Creek valley. The MEVC contains three named subplateaus, the largest and northernmost of which is the Big Raven Plateau. Its dominant feature is Mount Edziza which rises from within the middle of the plateau. Two lava fields are present on the Big Raven Plateau; the Desolation Lava Field at the northern end of the plateau covers more than 150 square kilometres (58 square miles) whereas
10032-427: The fault zone contain pressure ridges 10 to 40 centimetres (3.9 to 15.7 inches) high and 50 to 100 metres (160 to 330 feet) long, suggesting these faults are still active. This was confirmed by a local trapper in 1992 who noted that new pressure ridges appeared each year. The MEVC was originally subdivided into 15 geological formations , two of which are no longer used: The MEVC is a highly active volcanic system with
10164-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from
10296-503: The form of hot springs which exist along the western side of the volcanic complex. Future eruptions are likely to impact local streams and cause wildfires. Several streams surround the MEVC, many of which drain the flanks of the volcanic complex. They include the Little Iskut River along the southeastern flank, Kakiddi Creek along the northeastern flank, the Klastline River along the northern flank and Mess Creek along
10428-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which
10560-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in
10692-517: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in
10824-528: The guardian of fresh water in Tahltan folklore . It lies immediately south of Kounugu Mountain in the Spectrum Range and east of Ball Creek . Little Arctic Lake lies northeast of Arctic Lake near the northeastern flank of Wetalth Ridge. The MEVC is drained on all sides by streams within the Stikine River watershed . To the west, Mess Creek flows north along the Mess Creek Escarpment inside
10956-479: The highly fractured, poorly consolidated rocks comprising the MEVC. Most peaks greater than 2,130 metres (6,990 feet) in elevation have glaciers. Small separate glaciers are largely restricted to the southern half of the MEVC where they occur in the Spectrum Range, on Armadillo Peak and elsewhere. In contrast, Mount Edziza and Ice Peak are obscured by a relatively large ice cap that covers an area of 70 square kilometres (27 square miles). The western side of this ice cap
11088-408: The importance and size of the MEVC. The volcanic complex has since received very few geological studies. A three-year period of field studies conducted at the MEVC around 2007 focused on using volcano-ice interactions to constrain paleo-environmental conditions. The project was a collaboration between Ben Edwards of Dickinson College , Ian Skilling of the University of Pittsburgh , Barry Cameron of
11220-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include
11352-400: The last 7.5 million years during five cycles of magmatic activity which spanned four geologic epochs . Volcanic eruptions during these magmatic cycles produced a wide variety of volcanic rocks that comprise 13 geological formations . The most recent eruptions took place in the last 11,000 years but none of them have been precisely dated. Current activity occurs exclusively in
11484-571: The latter two of which occur in drier areas. Balsam poplar grows on delta soils and near lakes and creeks. The MEVC plateau is characterized by alpine and subalpine vegetation zones. The MEVC was covered by a regional ice sheet during the Pleistocene which receded and advanced periodically until about 11,000 years ago when deglaciation was essentially complete in a steadily warming climate. This warming trend ceased about 2,600 years ago, causing glaciers to advance from Mount Edziza, Ice Peak,
11616-468: The mean annual temperature is probably around −1 degree Celsius (30 degrees Fahrenheit) while the annual precipitation likely amounts to 400 millimetres (16 inches) of snow and rain. The mean annual temperature at an elevation of 1,390 metres (4,560 feet) is likely about −1 to −5 degrees Celsius (30 to 23 degrees Fahrenheit) where annual precipitation amounts to approximately 400 to 500 millimetres (16 to 20 inches). Arctic ground squirrels are abundant above
11748-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of
11880-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius
12012-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of
12144-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma
12276-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of
12408-421: The north fork of Tenchen Creek is Cinder Cliff , a 210-metre-high (690-foot) barrier of volcanic rocks. Koosick Bluff and Ornostay Bluff are just southwest of Mount Edziza near the head of Sezill Creek . Northwest and east of Coffee Crater are Hoia Bluff and Kaia Bluff, respectively. Hoia Bluff is a prominent west-facing cliff while Kaia Bluff is a steep-sided hill. On the northwestern side of Raspberry Pass
12540-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio
12672-681: The northeast from the eastern side of Mount Edziza, Shaman Creek and Sorcery Creek which flow to the east and north from near Kaia Bluff and Tsecha Creek which flows to the northeast from near Williams Cone. Shaman Creek contains one named tributary, Chakima Creek , which flows to the east and north. The rapidly eroding headwalls and steep spurs on the eastern side of the MEVC have deposited glacial and landslide debris into these tributaries. Transportion of this debris into Kakiddi Valley has produced several large alluvial fans behind which Kakiddi Lake, Mowchilla Lake, Mowdade Lake and Nuttlude Lake have formed. The lower eastern half and south end of
12804-454: The northwest, Tadekho Creek which flows to the northwest and Taweh Creek which flows to the northwest. Many of these Mess Creek tributaries also contain tributaries; the only named tributary of Elwyn Creek is Kadeya Creek which flows northwest from Mount Edziza . Kitsu Creek contains one named tributary, Nagha Creek , which flows northwest from the Spectrum Range. Walkout Creek is the only named tributary of Raspberry Creek; it flows west in
12936-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by
13068-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break
13200-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb
13332-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as
13464-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as
13596-532: The plateau surface rise up to 460 metres (1,500 feet) above the surrounding terrain , most of which occur in three lava fields. The Desolation Lava Field on the northern slope of Mount Edziza contains 10 cinder cones, namely Eve Cone , Storm Cone , Moraine Cone , Williams Cone , Sleet Cone , Twin Cone , Sidas Cone and the three Triplex Cones. Five named cones occur in the Snowshoe Lava Field on
13728-403: The plateau. Evidence of ice stagnation is present in the form of outflow channels, eskers , kames , kettles and morainal ridges on the northern side of the MEVC adjacent to Buckley Lake. Deglaciation of unstable and oversteepened valley walls has caused several landslides in the geologic past, especially along the Mess Creek Escarpment. This instability is attributed to the low-yield strength of
13860-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under
13992-522: The recreation area was greatly reduced in size to around 4,000 hectares (9,900 acres); it was eventually disestablished in 2003. Mount Edziza Provincial Park now covers an area of 266,180 hectares (657,700 acres), making it one of the largest provincial parks in British Columbia. Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from
14124-701: The remains of the Yukon Telegraph Line. This was a nearly 3,000-kilometre-long (1,900-mile) telegraphy system built by the Dominion Government Telegraph Service between 1897 and 1901 to send messages between Ashcroft, British Columbia in the south to Dawson City , Yukon in the north. A trail built to serve the line extended along much of its length and provided a route to the Yukon gold fields. Log cabins housing two men were built every 32 kilometres (20 miles) along
14256-621: The rest of the NCVP. Heart Peaks, Level Mountain and the MEVC are the largest NCVP centres by volume, the latter two having experienced volcanism for a much longer timespan than any other NCVP centre. Level Mountain, Hoodoo Mountain and the MEVC are the only NCVP centres that contain volcanic rocks of both mafic and intermediate to felsic composition. The highest of the four complexes is the MEVC at 2,786 metres (9,140 feet), followed by Level Mountain at 2,164 metres (7,100 feet), Heart Peaks at 2,012 metres (6,601 feet) and Hoodoo Mountain at 1,850 metres (6,070 feet). The most voluminous rocks comprising
14388-403: The result of alkali basaltic magma having undergone fractional crystallization in magma chambers on a longer timespan. Felsic peralkaline rocks such as trachyte, comendite and pantellerite form about 40% of the MEVC; they are the product of prolonged fractional crystallization of mantle-derived basaltic magma in magma chambers and mainly comprise lava domes and central volcanoes. Underlying
14520-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon
14652-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above
14784-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism
14916-631: The southeast from the eastern end of the Arctic Lake Plateau. Tributaries of the Little Iskut River include Stewbomb Creek , which flows eastwards from the eastern side of the Spectrum Range, and Bourgeaux Creek which flows to the east from Raspberry Pass. The only named tributary of Stewbomb Creek is Artifact Creek which flows to the southeast between Artifact Ridge and Obsidian Ridge. Bourgeaux Creek contains one named tributary, Gerlib Creek , which flows southwards from between Tadeda Peak and Armadillo Peak. Several small, unnamed streams drain
15048-477: The southwestern flank of Ice Peak: Tennena Cone , Keda Cone , Coffee Crater , Cocoa Crater and The Saucer . The Ash Pit is the only named cinder cone in the Mess Lake Lava Field which lies at the south-central end of the MEVC. Isolated cinder cones include Icefall Cone and Ridge Cone on the eastern slope of Mount Edziza, Nahta Cone at the extreme southern end of the MEVC, Kana Cone on
15180-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into
15312-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath
15444-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where
15576-547: The traditional territory of the Tahltan people which covers an area of more than 93,500 square kilometres (36,100 square miles). Historically, the MEVC was a significant source of obsidian for the Tahltan people. This volcanic glass was used in the manufacturing of projectile points and cutting blades which were widely traded throughout the Pacific Northwest . Obsidian from the MEVC has been recovered from archaeological sites in Alaska, Yukon, western Alberta and along
15708-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in
15840-556: The upper slopes but barren rock is abundant at higher elevations. Four central volcanoes dominate the MEVC, Mount Edziza being the highest with an elevation of 2,786 metres (9,140 feet). It is a large ice-covered stratovolcano rising well above the general level of the Tahltan Highland. Ice Peak is a composite stratovolcano 2,500 metres (8,200 feet) in elevation that has been reduced to a steep-walled pyramidal peak with active cirques on all of its sides. The Spectrum Range has an elevation of 2,430 metres (7,970 feet) and consists of
15972-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of
16104-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of
16236-421: The western flank. The valleys of these streams contain several species of trees, including white spruce , trembling aspen and lodgepole pine . Animal species such as birds, rodents, bears, sheep, goats, moose and caribou inhabit the area. Warm summers and cold, snowy winters characterize the climate at the MEVC; snow and ice remain on the highest volcanoes year-round. Indigenous peoples have lived adjacent to
16368-435: The western portion of the Spectrum Range is Nagha Glacier. Tenchen Glacier is a debris-covered glacier on the eastern side of Mount Edziza at the head of Tenchen Creek. South of Mount Edziza lies Tencho Glacier , the largest glacier of the MEVC. Tennaya Glacier lies at the head of Tennaya Creek on the southeastern side of Mount Edziza. The informally named Yeda Glacier existed at the head of Ball Creek south of Yeda Peak in
16500-563: The western side of Mess Creek where they attain an elevation of 760 metres (2,490 feet). Along the banks of Elwyn Creek at an elevation of 1,440 metres (4,720 feet) are the Elwyn Hot Springs which have created thick tufa deposits. The Taweh Hot Springs extend 0.5 kilometres (0.31 miles) along Sezill Creek at an elevation of 1,310 metres (4,300 feet) and emit thermal waters containing carbon dioxide ; extensive tufa deposits occur at these springs. Natural Resources Canada considers
16632-491: The western side of the MEVC. Southeast of the MEVC is 180 Lake, so-named because it is large enough for the Cessna 180 Skywagon to safely operate. The southern end of the MEVC is flanked by Arctic Lake which gets its name from the surrounding barren and treeless landscape. Two small lakes are named on the southern portion of the MEVC. At the head of the Little Iskut River is Little Ball Lake , also called Kounugu Lake after
16764-400: The western side of the fault has moved downward. The downthrowing of this fault during the Holocene may have been due to the draining of magma chambers following eruptions at the MEVC. The existence of peralkaline rocks at the MEVC and the presence of normal faults along Mess Creek valley support the conclusion that the MEVC lies in an area of continental rifting. Many tufa terraces along
16896-542: The youthful northern side of the MEVC. They flow north into the Klastline River and contain shallowly incised channels . The surrounding area is characterized by warm summers and cold, snowy winters; Mount Edziza itself is covered by snow year-round. Temperatures are warmest in mid-summer during the day when they may hit the 30 degrees Celsius (86 degrees Fahrenheit) range. However, temperatures can drop below freezing during summer nights, making snow or freezing rain
17028-402: Was carried out over the Stikine River area using a Bell helicopter. Souther began detailed mapping of the MEVC in 1965 when he was given the job of working on the volcanic complex by the Geological Survey of Canada. Japanese volcanologist Hisashi Kuno visited the MEVC with Souther in 1966; Kuno Peak in the Spectrum Range was named in his honour. A three-month period of earthquake monitoring
17160-493: Was conducted at the MEVC in 1968 after geologists of the Geological Survey of Canada suggested that there may still be magma movement under the volcanic complex. About 20 microearthquakes potentially associated with the MEVC were recorded by seismographs installed at Buckley Lake and Nuttlude Lake, but a seismological analysis suggested that they were of non-volcanic origin. The microearthquakes had magnitudes of around 0.5 which typically occur in many areas throughout
17292-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in
17424-795: Was further derived from the French word volcan (volcano), which was even further derived from Vulcanus , the Latin name of the Roman god of fire and metalworking . The Latin word is of Etruscan origin, but unknown meaning. Volcanologists research many aspects of volcanic processes to better understand planetary formation or to monitor current and future volcanic eruptions in order to protect citizens living in volcanic hazard zones. Volcanologists work at universities, museums or other national research institutes (often including volcano observatories), or in industry. Volcanologists working in academia will be usually involved in teaching geology classes if based at
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