70-686: Mount Cayley is an eroded but potentially active stratovolcano in the Pacific Ranges of southwestern British Columbia , Canada. Located 45 km (28 mi) north of Squamish and 24 km (15 mi) west of Whistler , the volcano resides on the edge of the Powder Mountain Icefield . It consists of massif that towers over the Cheakamus and Squamish river valleys . All major summits have elevations greater than 2,000 m (6,600 ft) , Mount Cayley being
140-520: A 200,000,000 to 300,000,000 m (7.1 × 10 to 1.06 × 10 cu ft) debris fan exposed along the Squamish River. A 0.5 to 40 cm (0.20 to 15.75 in) thick sequence of silts , sands and pebbles interbedded in the debris fan suggests that it may be the product of two major, closely spaced, debris avalanches rather than a single event. Another large debris avalanche about 1,100 years ago deposited material immediately upstream of
210-747: A 4-inch thick ash layer can weigh 120-200 pounds and can get twice as heavy when wet. Wet ash also poses a risk to electronics due to its conductive nature. Dense clouds of hot volcanic ash can be expelled due to the collapse of an eruptive column , or laterally due to the partial collapse of a volcanic edifice or lava dome during explosive eruptions . These clouds are known as pyroclastic surges and in addition to ash , they contain hot lava , pumice , rock , and volcanic gas . Pyroclastic surges flow at speeds over 50 mph and are at temperatures between 200 °C – 700 °C. These surges can cause major damage to property and people in their path. Lava flows from stratovolcanoes are generally not
280-485: A draping relief of 2,070 m (6,790 ft) , with a nearly vertical cliff more than 500 m (1,600 ft) high immediately above the Turbid Creek valley. Turbid Creek, Dusty Creek, Avalanche Creek and Shovelnose Creek flow from the slopes of Mount Cayley. Deep seismic profiling 12.5 to 13 km (7.8 to 8.1 mi) below the volcano has identified a large bright spot , a reflector interpreted to be
350-479: A fast moving mudflow . Lahars are typically about 60% sediment and 40% water. Depending on the abundance of volcanic debris the lahar can be fluid or thick like concrete. Lahars have the strength and speed to flatten structures and cause great bodily harm, gaining speeds up to dozens of kilometers per hour. In the 1985 eruption of Nevado del Ruiz in Colombia , Pyroclastic surges melted snow and ice atop
420-608: A favored food of the Squamish people, were gathered in large berry fields on and near the massif. Glassy rhyodacite collected from small outcrops on the slopes have been found in goat hunting sites and the Elaho rockshelter which have been collectively dated around 8,000 to 100 years old. Cayley rhyodacite has only been found in the northern parts of the Squamish Nation territory. There had been no first ascent of
490-515: A final intermediate composition . When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. The processes that trigger the final eruption remain a question for further research. Possible mechanisms include: These internal triggers may be modified by external triggers such as sector collapse , earthquakes , or interactions with groundwater . Some of these triggers operate only under limited conditions. For example, sector collapse (where part of
560-476: A jagged summit ridge of many slender rock pinnacles , the largest of which is known as the Vulcan's Thumb . Wizard Peak with an elevation of 2,240 m (7,350 ft) is east of Pyroclastic Peak and is the lowest of the three main summits. As a stratovolcano, Mount Cayley is built up of solidified lava and ash from successive volcanic eruptions. It is predominantly dacitic in composition, although rhyodacite
630-735: A logging road bridge and blocked the Squamish River, introducing massive quantities of sediment. The third event took place along Turbid Creek in June 2014 and involved a debris flow that removed part of the Squamish River Forest Service Road. The area has been inhabited by First Nations for thousands of years. Both the Mount Cayley volcano and The Black Tusk on the opposite side of the Cheakamus River valley are called taḵ'taḵmu'yin tl'a in7in'axa7en by
700-652: A mid- crustal magma chamber or body of very hot rock. Similar mid-crustal reflectors have been identified under subduction zone volcanoes in Japan. Mount Cayley has experienced volcanic eruptions sporadically for the last 4,000,000 years, making it one of the most persistent eruptive centres in the Garibaldi Volcanic Belt. Three primary eruptive stages in the history of the volcano have been identified. The Mount Cayley and Vulcan's Thumb stages occurred between 4,000,000 and 600,000 years ago with
770-769: A result of intraplate volcanism on oceanic islands far from plate boundaries. Examples are Teide in the Canary Islands , and Pico do Fogo in Cape Verde . Stratovolcanoes in the East African Rift include Ol Doinyo Lengai in Tanzania, and Longonot in Kenya. Subduction zone volcanoes form when hydrous minerals are pulled down into the mantle on the slab. These hydrous minerals, such as chlorite and serpentine , release their water into
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#1732775603818840-461: A significant threat to humans or animals because the highly viscous lava moves slowly enough for everyone to evacuate. Most deaths attributed to lava are due to related causes such as explosions and asphyxiation from toxic gas . Lava flows can bury homes and farms in thick volcanic rock which greatly reduces property value. However, not all stratovolcanoes erupt viscous and sticky lava . Nyiragongo , near Lake Kivu in central Africa ,
910-552: A steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas . The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity . The magma forming this lava is often felsic , having high to intermediate levels of silica (as in rhyolite , dacite , or andesite ), with lesser amounts of less viscous mafic magma . Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi). The term composite volcano
980-546: Is "promising" potential for a 100 megawatt geothermal power station at the volcano but the severe terrain makes development difficult and expensive. The heat source has also yet to be confirmed through deep drilling. Though Mount Cayley is currently quiet, it still poses potential hazards to nearby towns as well as logging and recreational areas. GSC seismic data suggest that the volcano still contains magma, indicating possible future eruptive activity and associated volcanic hazards such as landslides. An eruption scenario for
1050-479: Is Mount Cayley with an elevation of 2,385 m (7,825 ft) . Its northeastern flank abuts the southern end of the Powder Mountain Icefield. This is a 9 km (5.6 mi) long and 5 km (3.1 mi) wide irregularly-shaped glacier that trends slightly to the northwest. Just southwest of Mount Cayley lies Pyroclastic Peak , 2,341 m (7,680 ft) in elevation. It contains
1120-472: Is a local high amplitude seismic attribute anomaly that can indicate the presence of hydrocarbons and is therefore known as a direct hydrocarbon indicator . It is used by geophysicists in hydrocarbon exploration . Bright spots were not commonly identified until the early 1970s because of the extensive and industry-wide use of automatic gain control , which obscured the amplitude effects of hydrocarbon accumulations. A bright spot primarily results from
1190-480: Is a passive release of gas during periods of dormancy. As per the above examples, while eruptions like Mount Unzen have caused deaths and local damage, the impact of the June 1991 eruption of Mount Pinatubo was seen globally. The eruptive columns reached heights of 40 km and dumped 17 megatons of SO 2 into the lower stratosphere . The aerosols that formed from the sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), and other gases dispersed around
1260-420: Is also common. Its original and current volumes remain uncertain. It may have had a volume as large as 13 km (3.1 cu mi) , but erosion has since reduced it to glacially eroded crags. The modern volcano has an estimated volume of 8 km (1.9 cu mi) and is only a modest fraction of its total output of silicic eruptive products. It has a proximal relief of 550 m (1,800 ft) and
1330-451: Is the most famous example of a hazardous stratovolcano eruption. It completely smothered the nearby ancient cities of Pompeii and Herculaneum with thick deposits of pyroclastic surges and pumice ranging from 6–7 meters deep. Pompeii had 10,000-20,000 inhabitants at the time of eruption. Mount Vesuvius is recognized as one of the most dangerous of the world's volcanoes, due to its capacity for powerful explosive eruptions coupled with
1400-450: Is typically between 700 and 1,200 °C (1,300-2,200 °F). Volcanic bombs are masses of unconsolidated rock and lava that are ejected during an eruption. Volcanic bombs are classified as larger than 64mm (2.5 inches). Anything below 64mm is classified as a volcanic block . When erupted Bombs are still molten and partially cool and solidify on their descent. They can form ribbon or oval shapes that can also flatten on impact with
1470-1014: Is used because the strata are usually mixed and uneven instead of neat layers. They are among the most common types of volcanoes; more than 700 stratovolcanoes have erupted lava during the Holocene Epoch (the last 11,700 years), and many older, now extinct, stratovolcanoes erupted lava as far back as Archean times. Stratovolcanoes are typically found in subduction zones but they also occur in other geological settings. Two examples of stratovolcanoes famous for catastrophic eruptions are Krakatoa in Indonesia (which erupted in 1883 claiming 36,000 lives) and Mount Vesuvius in Italy (which erupted in 79 A.D killing an estimated 2,000 people). In modern times, Mount St. Helens (1980) in Washington State , US, and Mount Pinatubo (1991) in
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#17327756038181540-403: Is very dangerous because its magma has an unusually low silica content , making it much less viscous than other stratovolcanoes. Low viscosity lava can generate massive lava fountains , while lava of thicker viscosity can solidify within the vent, creating a volcanic plug . Volcanic plugs can trap gas and create pressure in the magma chamber, resulting in violent eruptions. Lava
1610-693: The Geological Survey of Canada (GSC). Eruption impact would be largely a result of the concentration of vulnerable infrastructure in nearby valleys. The volcano resides in the middle of a north–south trending zone of volcanism called the Mount Cayley volcanic field . It consists predominantly of volcanoes that formed subglacially during the Late Pleistocene age , such as Pali Dome , Slag Hill , Ring Mountain and Ember Ridge , but activity continued at Pali Dome and Slag Hill into
1680-848: The Holocene epoch . The Mount Cayley volcanic field is part of the Garibaldi Volcanic Belt , which in turn represents a northern extension of the Cascade Volcanic Arc . Volcanism of the Cascade Arc is largely a result of the Juan de Fuca Plate sliding under the North American Plate at the Cascadia subduction zone . Three main summits comprise the Mount Cayley massif. The highest and northernmost
1750-579: The Philippines have erupted catastrophically, but with fewer deaths. Stratovolcanoes are common at subduction zones , forming chains and clusters along plate tectonic boundaries where an oceanic crust plate is drawn under a continental crust plate (continental arc volcanism, e.g. Cascade Range , Andes , Campania ) or another oceanic crust plate ( island arc volcanism, e.g. Japan , Philippines , Aleutian Islands ). Stratovolcanoes also occur in some other geological settings, for example as
1820-679: The Squamish people . In their language it means "Landing Place of the Thunderbird". The Thunderbird is a legendary creature in North American indigenous peoples' history and culture. When the bird flaps its wings, thunder is created, and lightning originates from its eyes. Mount Cayley and The Black Tusk are considered sacred to the Squamish people as they have played an important part of their history . Mountain bilberries , Canadian blueberries and oval-leaved blueberries , being
1890-891: The magma is too viscous 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 high speed and 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 often 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 over 150 km/h (90 mph). Around 30,000 people were killed by pyroclastic flows during
1960-443: The mantle which decreases its melting point by 60 to 100 °C. The release of water from hydrated minerals is termed " dewatering ", and occurs at specific pressures and temperatures for each mineral, as the plate descends to greater depths. This allows the mantle to partially melt and generate magma . This is called flux melting . The magma then rises through the crust , incorporating silica-rich crustal rock, leading to
2030-616: The 1902 eruption of Mount Pelée on the island of Martinique in the Caribbean . During March and April 1982, El Chichón in the State of Chiapas in southeastern Mexico , erupted 3 times, causing the worst volcanic disaster in that country's history and killied more than 2,000 people in pyroclastic flows . Two Decade Volcanoes that erupted in 1991 provide examples of stratovolcano hazards. On 15 June, Mount Pinatubo erupted and caused an ash cloud to shoot 40 km (25 mi) into
2100-485: The 1982 eruption of Galunggung in Java , British Airways Flight 9 flew into the ash cloud, causing it to sustain temporary engine failure and structural damage. Although no crashes have happened due to ash, more than 60, mostly commercial aircraft , have been damaged. Some of these incidents resulted in emergency landings. Ashfalls are a threat to health when inhaled and are also a threat to property. A square yard of
2170-585: The 5,321 m (17,457 ft) high Andean volcano. The ensuing lahar killed 25,000 people and flooded the city of Armero and nearby settlements. As a volcano forms, several different gases mix with magma in the volcanic chamber. During an eruption the gases are then released into the atmosphere which can lead to toxic human exposure. The most abundant of these gases is H 2 O ( water ) followed by CO 2 ( carbon dioxide ), SO 2 ( sulfur dioxide ), H 2 S ( hydrogen sulfide ), and HF ( hydrogen fluoride ). If at concentrations of more than 3% in
Mount Cayley - Misplaced Pages Continue
2240-574: The Juan de Fuca slab after the formation of the Explorer Plate. The early Mount Cayley stage was characterized by the eruption of felsic lava flows and pyroclastic rocks onto a crystalline basement . Initial volcanism formed a southwesterly- dipping prism of dacite flows and tephra cut by several dikes and sills . These rocks have been hydrothermally altered to varying degrees and are light yellow or red in colour. They are well exposed in
2310-672: The Squamish and Cheakamus valleys. These would rapidly melt snow and ice in the summit area, generating debris flows that could reach Squamish and Daisy Lake , damaging much infrastructure. Heavy ash falls would occur in the Vancouver area, the Fraser Valley , Bellingham , Kamloops, Whistler and Pemberton . The ash would damage power and communication lines and satellite dishes, as well as computer and other electrical equipment. Telephone, radio, cell phone and satellite communications would be cut off. Weak structures could collapse under
2380-469: The Vulcan's Thumb stage, built an edifice that grew upon the southwestern slope of the ancestral Mount Cayley stratovolcano. This began with the eruption of massive dacite flows and blocky agglutinated breccias onto basement and older volcanic rocks of the Mount Cayley stage. These rocks partially form a ridge south of Wizard Peak and comprise the prominent summit ridge pinnacles of Pyroclastic Peak, including
2450-447: The Vulcan's Thumb stage. Because Mount Cayley is rich in coarse proximal pyroclastic deposits, some of them hydrothermally altered, it is especially prone to slope failure and debris avalanches . At least three major debris avalanches have occurred from the western slope in the last 10,000 years, all of which blocked the Squamish River and formed temporary lakes upstream. The first and largest event about 4,800 years ago produced
2520-484: The Vulcan's Thumb. Later activity produced an overlying 1 km (0.62 mi) wide and 4 km (2.5 mi) long southwest-trending lobe of unconsolidated or poorly consolidated tephra. The tephra consists of ash and lapilli -sized fragments that have been heavily eroded to form vertical cliffs and ridges. Volcanism also deposited a 130 m (430 ft) thick sequence of blocky dacitic tuff breccia between Wizard Peak and Mount Cayley. Volcanic activity of
2590-521: The Whistler–Pemberton area, followed by weeks of viscous lava dome growth punctuated by small explosions. The explosions would generate short-lived 10 to 15 km (6.2 to 9.3 mi) high plumes, small pyroclastic flows to the Squamish and Cheakamus valleys and ash plumes to the north and east. Explosions might cease and be replaced by slow, continuous growth of a lava dome in the new crater . Rain and seasonal snow melt would regularly remobilize
2660-819: The air, when breathed in CO 2 can cause dizziness and difficulty breathing. At more than 15% concentration CO 2 causes death. CO 2 can settle into depressions in the land, leading to deadly, odorless pockets of gas. SO 2 classified as a respiratory, skin, and eye irritant if come into contact with. It is known for its pungent egg smell and role in ozone depletion and has the potential to cause acid rain downwind of an eruption. H 2 S has an even stronger odor than SO 2 as well as being even more toxic. Exposure for less than an hour at concentrations of over 500 ppm causes death. HF and similar species can coat ash particles and once deposited can poison soil and water. Gases are also emitted during volcanic degassing, which
2730-748: The air. It produced large pyroclastic surges and lahar floods that caused a lot of damage to the surrounding area. Pinatubo , located in Central Luzon just 90 km (56 mi) west-northwest of Manila , had been dormant for six centuries before the 1991 eruption. This eruption was one of the 2nd largest in the 20th century. It produced a large volcanic ash cloud that affected global temperatures, lowering them in areas as much as .5 °C. The volcanic ash cloud consisted of 22 million tons of SO 2 which combined with water droplets to create sulfuric acid . In 1991 Japan's Unzen Volcano also erupted, after 200 years of inactivity. It's located on
2800-660: The construction of the stratovolcano and plug domes . A 300,000-year-long period of quiescence followed, during which prolonged erosion destroyed much of the original volcanic structure. This was followed by the third and final Shovelnose stage about 300,000 to 200,000 years ago with the emplacement of parasitic lava domes and flows. Although one of the Shovelnose domes has been potassium-argon dated at 310,000 years old, this date may be in error from excess argon . The Shovelnose stage rocks could be much younger, perhaps less than 15,000 years old. Eruptions during
2870-421: The creation of lakes that eventually overtopped and breached the landslide dam to produce floods and possibly debris flows which in turn swept down Turbid Creek far beyond the landslide terminus. In June 1984, a major rockslide and debris flow resulted from a 3,200,000 m (110,000,000 cu ft) collapse at the head of Avalanche Creek. The debris flow reached the mouth of Turbid Creek where it destroyed
Mount Cayley - Misplaced Pages Continue
2940-548: The east and west sides of the volcano in 1980–1982 by Nevin Sadlier-Brown Goodbrand Limited on behalf of the GSC showed geothermal gradients ranging from 45 to 95 millikelvin per metre. In 2002, BC Hydro published a report identifying 16 prospective geothermal sites throughout British Columbia. They named Mount Cayley as one of the six sites with the highest potential for commercial development. There
3010-508: The event of an explosive eruption, an ash plume could reach 20 km (12 mi) in height and may be maintained for 12 hours. Air traffic would be diverted from the area and all airports covered by the plume would be closed, notably those in Vancouver , Victoria , Kamloops , Prince George and Seattle . Above the vent area, material from the eruption plume would collapse to form pyroclastic flows and would flow east and west into
3080-413: The failure of a large volcanic block consisting of poorly consolidated tuff breccia and columnar-jointed dacite. The mass slid into Dusty Creek where it quickly fragmented into an aggregate then travelled roughly 1 km (0.62 mi) downstream where it entered the broader flatter valley of Turbid Creek for an additional 1 km (0.62 mi) . Both creeks were blocked by the event, resulting in
3150-433: The final Shovelnose stage involved the eruption of two lava domes at the east and southeast margins of Mount Cayley in the upper Shovelnose Creek valley. The southeast dacite dome forms 400 m (1,300 ft) high cliffs of small diameter columnar joints. It was the source of a 5 km (3.1 mi) long dacite flow that extends down the Shovelnose and Turbid creek valleys to near the Squamish River. The east lava dome
3220-435: The first two of which built most of the volcano. The latest eruptive period occurred sometime in the last 400,000 years with lesser activity continuing into the present day. Future eruptions are likely to threaten neighbouring communities with pyroclastic flows , lahars (volcanically induced mudslides , landslides and debris flows ) and floods. To monitor this threat, the volcano and its surroundings are monitored by
3290-540: The flank of a volcano collapses in a massive landslide) can only trigger the eruption of a very shallow magma chamber . Magma differentiation and thermal expansion also are ineffective as triggers for eruptions from deep magma chambers . In recorded history , explosive eruptions at subduction zone ( convergent-boundary ) volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens , Mount Etna and Mount Pinatubo , typically erupt with explosive force because
3360-401: The forecasting of catastrophic events. If eruptive activity were to resume, scientists would likely be able to detect increased seismicity as magma makes its way through the crust. The abundance of seismic activity and the sensitivity of the existing Canadian National Seismograph Network in this area would alert the GSC and possibly trigger an expanded monitoring effort. As the magma nears
3430-478: The ground. Volcanic Bombs are associated with Strombolian and Vulcanian eruptions and basaltic lava . Ejection velocities ranging from 200 to 400 m/s have been recorded causing volcanic bombs to be destructive. Lahars (from a Javanese term for volcanic mudflows) are a mixture of volcanic debris and water. Lahars can result from heavy rainfall during or before the eruption or interaction with ice and snow. Meltwater mixes with volcanic debris causing
3500-458: The high population density of the surrounding Metropolitan Naples area (totaling about 3.6 million inhabitants). In addition to potentially affecting the climate, volcanic ash clouds from explosive eruptions pose a serious hazard to aviation . Volcanic ash clouds consist of ash which is made of silt or sand sized pieces of rock, mineral, volcanic glass . Ash grains are jagged, abrasive, and don't dissolve in water. For example, during
3570-465: The highest at 2,385 m (7,825 ft) . The surrounding area has been inhabited by indigenous peoples for more than 7,000 years while geothermal exploration has taken place there for the last four decades. Part of the Garibaldi Volcanic Belt , Mount Cayley was formed by subduction zone volcanism along the western margin of North America. Eruptive activity began about 4,000,000 years ago and has since undergone three stages of growth,
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#17327756038183640-447: The increase in acoustic impedance contrast when a hydrocarbon (with a lower acoustic impedance) replaces the brine-saturated zone (with a higher acoustic impedance) that underlies a shale (with a higher acoustic impedance still), increasing the reflection coefficient . The effect decreases with depth because compaction for sands and shales occurs at different rates and the acoustic impedance relationship stated above will not hold after
3710-452: The island of Kyushu about 40 km (25 mi) east of Nagasaki . Beginning in June, a newly formed lava dome repeatedly collapsed. This generated a pyroclastic flow that flowed down the mountain's slopes at speeds as high as 200 km/h (120 mph). The 1991 eruption of Mount Unzen was one of the worst volcanic disasters in Japan's history, once killing more than 15,000 people in 1792. The eruption of Mount Vesuvius in 79 AD
3780-482: The lava dome might produce small explosions, ash plumes and pyroclastic flows. Squamish would remain evacuated, Highway 99 would remain closed and unrepairable and travel between Whistler/Pemberton and Vancouver would be forced to go via a much longer route to the east. Eruptive activity itself could go on for years, followed by years of declining secondary activity. The cooling lava would intermittently spall sections to produce pyroclastic flows. The fragmental material on
3850-577: The massif until July 1928 when an Alpine Club of Canada party, consisting of mountaineers R. E. Knight, W. G. Wheatley, E. C. Brooks, T. Fyles and B. Clegg, climbed Mount Cayley. Fyles submitted the mountain name to the Government of British Columbia in September 1928 for Beverley Cochrane Cayley , a mountaineer and friend of those in the climbing expedition who had died in June that year. The name became official on April 2, 1929, and photographs of
3920-537: The mouth of Turbid Creek. The third event followed about 500 years ago with the deposition of two diamicton units along Turbid Creek and was the smallest of the three major prehistoric debris avalanches. A lack of organic and paleosol horizons between the two units implies that they most likely represent separate surges within the same debris avalanche event. At least three smaller scale debris avalanches have occurred in historic time. A 5,000,000 m (180,000,000 cu ft) landslide occurred in 1963 with
3990-531: The peak were published with Fyles' description of first ascent in the 1931 Canadian Alpine Journal Vol XX. Mount Cayley has been investigated as a potential geothermal energy resource since at least the late 1970s. Geothermal exploration by Energy, Mines and Resources Canada commenced in 1977 with the drilling of two shallow boreholes on the west side of the volcano for temperature observation. High geothermal gradients of 51 and 65 millikelvin per metre were obtained from this work. Further drilling on
4060-429: The prominent southwestern cliffs of the volcano. Subsequent activity deposited a series of massive dacite flows up to 150 m (490 ft) thick, which form the summit and northern slope of Wizard Peak. The Mount Cayley stage culminated with the emplacement of a central plug dome that forms the narrow jagged summit ridge of Mount Cayley. This edifice consists of similar intrusive dacite. The next eruptive period,
4130-654: The regional plate tectonics . This involved the separation of the Explorer and Juan de Fuca plates off the British Columbia Coast , which had some significant ramifications for regional geologic evolution. After this reorganization ceased, volcanism shifted westward from the Pemberton Volcanic Belt to establish the younger and currently active Garibaldi Volcanic Belt. The westward shift in volcanism may have been related to steepening of
4200-464: The size of Mount Pinatubo affected the weather for a few years; with warmer winters and cooler summers observed. A similar phenomenon occurred in the April 1815, the eruption of Mount Tambora on Sumbawa island in Indonesia . The Mount Tambora eruption is recognized as the most powerful eruption in recorded history. Its eruption cloud lowered global temperatures as much as 0.4 to 0.7 °C. In
4270-504: The slopes and in valleys would be periodically remobilized into debris flows. Significant structural mitigation would have to be built to reclaim use of the Highway 99 corridor and Squamish area. Stratovolcano A stratovolcano , also known as a composite volcano , is a conical volcano built up by many alternating layers ( strata ) of hardened lava and tephra . Unlike shield volcanoes , stratovolcanoes are characterized by
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#17327756038184340-573: The surface, the volcano would likely swell and the surface fracture, causing greatly increased vigour in the hot springs and the creation of new springs or fumaroles . Minor and possibly large landslides could occur and might temporarily block the Squamish River, as has happened in the past without earthquake shaking and intrusion-related deformation. Eventually the near-surface magma may cause phreatic explosions and debris flows. By this time Highway 99 would be closed, Squamish would be evacuated and Whistler would be at least considered for evacuation. In
4410-581: The tephra into lahars and these would continue to threaten the Squamish and Cheakamus valleys. The solidifying, spreading lava could then generate rockfalls and form a voluminous talus apron into the Squamish valley. As the lava dome spreads, it would periodically undergo gravitational collapse to generate dense pyroclastic flows into the Squamish and Cheakamus valleys. Ash elutriated from the pyroclastic flows would form plumes up to 10 km (6.2 mi) high, again dropping ash onto Pemberton and Whistler and causing disruptions to local air traffic. Infrequently,
4480-546: The three stages produced volcanic rocks of felsic and intermediate compositions, including andesite , dacite and rhyodacite. The lack of evidence for volcano-ice interactions at Mount Cayley implies that all eruptive stages most likely took place prior to glacial periods . This contrasts with many neighbouring volcanoes, which contain abundant volcanic glass and fine-scale columnar jointing from contact with ice during eruptions. Initial volcanic activity of Mount Cayley 4,000,000 years ago corresponded with changes to
4550-466: The volcano to be potentially active. Temperatures ranging from 18 to 40 °C (64 to 104 °F) have been measured from the hot springs. The existence of hot springs indicate that magmatic heat is still present. Extensive tufa and sinter deposits inhabit the main hot springs while bright red ferruginous ochre precipitates from several cold seeps in the vicinity. The springs are confined around dacite cupolas and dikes that were emplaced during
4620-407: The volcano was organized by GSC scientists in 2000 to show how Western Canada is vulnerable to such an event. They based the scenario on past activity in the Garibaldi Volcanic Belt and involved both explosive and effusive activity. The scenario was published in 2003 as an article for Natural Hazards , a Springer journal devoting on all aspects of natural hazards including risk management and
4690-432: The weight of the ash. The eruption plume would then spread to envelop most of the west coast from Seattle to Anchorage , causing all enclosed airports to be closed and all relevant flights to be diverted or cancelled. Eastward migration of the plume would disrupt air traffic across Canada from Alberta to Newfoundland and Labrador . Ash from further, minor explosive activity could continue to fall lightly but persistently in
4760-412: The world. The SO 2 in this cloud combined with water (both of volcanic and atmospheric origin) and formed sulfuric acid , blocking a portion of the sunlight from reaching the troposphere . This caused the global temperature to decrease by about 0.4 °C (0.72 °F) from 1992 to 1993. These aerosols caused the ozone layer to reach the lowest concentrations recorded at that time. An eruption
4830-472: The year following the eruption, most of the Northern Hemisphere experienced cooler temperatures during the summer. In the northern hemisphere , 1816 was known as the " Year Without a Summer ". The eruption caused crop failures, food shortages, and floods that killed over 100,000 people across Europe , Asia , and North America . Bright spot In reflection seismology , a bright spot
4900-447: Was built upon blocky bedded tephra overlying basement rocks and consists of a steep-sided columnar jointed mass of dacite. Although Mount Cayley is not known to have had historical volcanic eruptions, low-level activity has continued into recorded history . Shallow earthquakes have occurred in the vicinity since 1985 and the Shovelnose and Turbid creek valleys contain two and three hot springs , respectively. The GSC therefore considers
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