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73-546: The caldera complex is around 2.7 billion years old, consisting of a series of overlapping calderas of various ages and sizes. It lies within the southern zone of the Abitibi greenstone belt of the Superior Craton and has an area of 3,000 km (1,200 sq mi) . The Blake River Megacaldera Complex has been a centre of major interest since 2006 with numerous excursions at the international, national and local level. It

146-413: A " volcanic winter ", similar to a nuclear winter because of the overall decrease in temperatures and abysmal farming conditions. Climate data have shown that the variance between daily lows and highs may have played a role in the lower average temperature because the fluctuations were much more subdued. Generally, the mornings were warmer because of nightly cloud cover and the evenings were cooler because

219-428: A 1998 journal article authored by J. Tanguy and others claimed that Petroeschevsky's figures were unfounded and based on untraceable references. Tanguy's revision of the death toll was based on Zollinger's work on Sumbawa for several months after the eruption and on Thomas Raffles 's notes. Tanguy pointed out that there may have been additional victims on Bali and East Java because of famine and disease. Their estimate

292-479: A 500 km (300 mi) radius saw a 5 cm (2 in) ash fall, and ash could be found as far away as 1,300 km (810 mi). The ash burned and smothered crops, creating an immediate shortage of food in Indonesia.(Cole-Dai et al. 2009) The ejection of these gases, especially hydrogen chloride , caused the precipitation to be extremely acidic, killing much of the crops that survived or were rebudding during

365-409: A caldera, possibly an ash-flow caldera. The volcanic activity of Mars is concentrated in two major provinces: Tharsis and Elysium . Each province contains a series of giant shield volcanoes that are similar to what we see on Earth and likely are the result of mantle hot spots . The surfaces are dominated by lava flows, and all have one or more collapse calderas. Mars has the tallest volcano in

438-475: A chamber, greatly diminishing its capacity to support its own roof, and any substrate or rock resting above. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater , the feature is actually a type of sinkhole , as it is formed through subsidence and collapse rather than an explosion or impact. Compared to

511-538: A change will be measured even in the most local of environments. When volcanoes erupt, they eject carbon dioxide (CO 2 ), water, hydrogen, sulfur dioxide (SO 2 ), hydrogen chloride , hydrogen fluoride , and many other gases (Meronen et al. 2012). CO 2 and water are greenhouse gases , which comprise 0.0415 percent and 0.4 percent of the atmosphere, respectively. Their small proportion disguises their significant role in trapping solar radiation and reradiating it back to Earth. The 1815 eruption released SO 2 into

584-400: A diameter of 290 km (180 mi). The average caldera diameter on Mars is 48 km (30 mi), smaller than Venus. Calderas on Earth are the smallest of all planetary bodies and vary from 1.6–80 km (1–50 mi) as a maximum. The Moon has an outer shell of low-density crystalline rock that is a few hundred kilometers thick, which formed due to a rapid creation. The craters of

657-467: A magma chamber whose magma is rich in silica . Silica-rich magma has a high viscosity , and therefore does not flow easily like basalt . The magma typically also contains a large amount of dissolved gases, up to 7 wt% for the most silica-rich magmas. When the magma approaches the surface of the Earth, the drop in confining pressure causes the trapped gases to rapidly bubble out of the magma, fragmenting

730-399: A meganested caldera complex. Caldera A caldera ( / k ɔː l ˈ d ɛr ə , k æ l -/ kawl- DERR -ə, kal- ) is a large cauldron -like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption . An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such

803-583: A noticeable drop in temperature around the world. Large calderas may have even greater effects. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia . At some points in geological time , rhyolitic calderas have appeared in distinct clusters. The remnants of such clusters may be found in places such as the Eocene Rum Complex of Scotland,

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876-694: A similar complaint. All vegetation on the island was destroyed. Uprooted trees, mixed with pumice ash, washed into the sea and formed rafts up to five km (three mi) across. Between 1 and 3 October the British ships Fairlie and James Sibbald encountered extensive pumice rafts about 3,600 km (2,200 mi) west of Tambora. Clouds of thick ash still covered the summit on 23 April. Explosions ceased on 15 July, although smoke emissions were observed as late as 23 August. Activity resumed in August 1819—a small eruption with "flames" and rumbling aftershocks , and

949-495: A supposed ship in distress. The explosion had an estimated VEI of 7. An estimated 41 km (10 cu mi) of pyroclastic trachyandesite were ejected, weighing about 10 billion tonnes . This left a caldera measuring 6–7 km ( 3 + 1 ⁄ 2 – 4 + 1 ⁄ 2  mi) across and 600–700 m (2,000–2,300 ft) deep. The density of fallen ash in Makassar was 636 kg/m (39.7 lb/cu ft). Before

1022-402: A volcanic eruption in 1809 may also have contributed to a reduction in global temperatures. By most calculations, the eruption of Tambora was at least a full order of magnitude (10 times) larger than that of Mount Pinatubo in 1991.(Graft et al. 1993) Its energy release was equivalent to about 33 gigatons of TNT (1.4 × 10   J ). An estimated 1,220 m (4,000 ft) of the top of

1095-493: Is a volcano on the island of Sumbawa in present-day Indonesia , then part of the Dutch East Indies , and its 1815 eruption was the most powerful volcanic eruption in recorded human history . This eruption, with a volcanic explosivity index (VEI) of 7, ejected 37–45 km (8.9–10.8 cubic miles) of dense-rock equivalent (DRE) material into the atmosphere, and was the most recent confirmed VEI-7 eruption. Although

1168-400: Is a world-class metallotect with respect to both hydrothermal Cu - Zn massive sulfides and gold -rich massive sulfides. The Blake River Megacaldera Complex consists of mainly mafic to intermediate volcanic flows and less abundant felsic volcanic flows and intercalated pyroclastic rocks , which underwent three stages of major volcanic activity. The Blake River Megacaldera Complex

1241-721: Is again contrasted by the unusually low precipitations in 1818, which caused droughts throughout most of Europe and Asia.(Auchmann et al. 2012) Russia had already experienced unseasonably warm and dry summers since 1815 and this continued for the next three years. There are also documented reductions in ocean temperature near the Baltic Sea , the North Sea, and the Mediterranean Sea. This seems to have been an indicator of shifted oceanic circulation patterns and possibly changed wind direction and speed.(Meronen et al. 2012) Taking into account

1314-643: Is considered a supervolcano due to its great size and its multiple dikes and vents. The Misema Caldera is in the order of 3,500 to 4,000 km (1,400 to 1,500 sq mi) , making the complex similar to the Yellowstone Caldera in Wyoming , Lake Toba in Indonesia and strikingly similar in structure to the Olympus Mons caldera on Mars . As a result, the Blake River Group is best categorized as

1387-405: Is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A roughly circular fracture , the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are also known as ring dikes . Secondary volcanic vents may form above the ring fracture. As the magma chamber empties, the center of the volcano within

1460-571: Is heated by solid flexing due to the tidal influence of Jupiter and Io's orbital resonance with neighboring large moons Europa and Ganymede , which keep its orbit slightly eccentric . Unlike any of the planets mentioned, Io is continuously volcanically active. For example, the NASA Voyager 1 and Voyager 2 spacecraft detected nine erupting volcanoes while passing Io in 1979. Io has many calderas with diameters tens of kilometers across. 1815 eruption of Mount Tambora Mount Tambora

1533-529: Is relatively young (1.25 million years old) and unusually well preserved, and it remains one of the best studied examples of a resurgent caldera. The ash flow tuffs of the Valles caldera, such as the Bandelier Tuff , were among the first to be thoroughly characterized. About 74,000 years ago, this Indonesian volcano released about 2,800 cubic kilometres (670 cu mi) dense-rock equivalent of ejecta. This

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1606-564: The British Isles . Families in Wales travelled long distances as refugees, begging for food. Famine was prevalent in north and southwest Ireland, following the failure of wheat, oat, and potato harvests. The crisis was severe in Germany, where food prices rose sharply, and demonstrations in front of grain markets and bakeries, followed by riots, arson, and looting, took place in many European cities. It

1679-810: The Molucca Islands 1,400 km (870 mi) away. On the morning of 6 April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be the sound of firing guns was heard on 10 April in Trumon, Sumatra , more than 2,600 km (1,600 mi) away. New analysis and agreements in dates suggest the rumbles of Tambora were heard even further in Nong Khai at 3352 km (2061 miles) away, Vientiane at 3368 km (2072 miles) away, and perhaps Mukdahan at 3117 km (1919 miles) away. At about 19:00 on 10 April,

1752-500: The San Juan Mountains of Colorado , where the 5,000 cubic kilometres (1,200 cu mi) Fish Canyon Tuff was blasted out in eruptions about 27.8 million years ago. The caldera produced by such eruptions is typically filled in with tuff, rhyolite , and other igneous rocks . The caldera is surrounded by an outflow sheet of ash flow tuff (also called an ash flow sheet ). If magma continues to be injected into

1825-657: The exsolution of a high-pressure fluid magma formed during cooling and crystallisation of the magma. An over-pressurization of the chamber of about 4,000–5,000 bar (400–500 MPa; 58,000–73,000 psi) was generated, with the temperature ranging from 700–850 °C (1,290–1,560 °F). In 1812, the volcano began to rumble and generated a dark cloud. On 5 April 1815, a giant eruption occurred, followed by thunderous detonation sounds heard in Makassar on Sulawesi 380 km (240 mi) away, Batavia (now Jakarta ) on Java 1,260 km (780 mi) away, and Ternate on

1898-471: The "Year Without a Summer". Average global temperatures decreased by about 0.4 to 0.7 °C (0.7 to 1.3 °F), enough to cause significant agricultural problems around the globe. On 4 June 1816, frosts were reported in the upper elevations of New Hampshire, Maine (then part of Massachusetts), Vermont, and northern New York. On 6 June 1816, snow fell in Albany, New York and Dennysville, Maine . On 8 June 1816,

1971-440: The 1815 eruption occurred during a Dalton Minimum , a period of unusually low solar radiation. Volcanism plays a large role in climate shifts, both locally and globally. This was not always understood and did not enter scientific circles as fact until the 1883 eruption of Krakatoa tinted the skies orange. The scale of the volcanic eruption will determine the significance of the impact on climate and other chemical processes, but

2044-642: The Dalton Minimum and the presence of famine and droughts predating the eruption, the Tambora eruption accelerated or exacerbated the extreme climate conditions of 1815. While other eruptions and other climatological events would have led to a global cooling of about 0.2 °C (0.4 °F), Tambora increased on that benchmark substantially. Source: Oppenheimer (2003), and Smithsonian Global Volcanism Program for VEI. [REDACTED]  This article incorporates public domain material from websites or documents of

2117-417: The Earth's volcanic activity (the other 40% is attributed to hotspot volcanism). Caldera structure is similar on all of these planetary bodies, though the size varies considerably. The average caldera diameter on Venus is 68 km (42 mi). The average caldera diameter on Io is close to 40 km (25 mi), and the mode is 6 km (3.7 mi); Tvashtar Paterae is likely the largest caldera with

2190-661: The English term cauldron is also used, though in more recent work the term cauldron refers to a caldera that has been deeply eroded to expose the beds under the caldera floor. The term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands , where he first saw the Las Cañadas caldera on Tenerife , with Mount Teide dominating

2263-510: The Moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but are currently believed to have been formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed. Around 500 million years afterward, the Moon's mantle was able to be extensively melted due to the decay of radioactive elements. Massive basaltic eruptions took place generally at

Blake River Megacaldera Complex - Misplaced Pages Continue

2336-565: The Mount Tambora eruption reached a violent climax on 10 April 1815, increased steaming and small phreatic eruptions occurred during the next six months to three years. The ash from the eruption column dispersed around the world and lowered global temperatures in an event sometimes known as the Year Without a Summer in 1816. This brief period of significant climate change triggered extreme weather and harvest failures in many areas around

2409-647: The San Juan Mountains of Colorado (formed during the Oligocene , Miocene , and Pliocene epochs) or the Saint Francois Mountain Range of Missouri (erupted during the Proterozoic eon). For their 1968 paper that first introduced the concept of a resurgent caldera to geology, R.L. Smith and R.A. Bailey chose the Valles caldera as their model. Although the Valles caldera is not unusually large, it

2482-720: The Solar System, Olympus Mons , which is more than three times the height of Mount Everest, with a diameter of 520 km (323 miles). The summit of the mountain has six nested calderas. Because there is no plate tectonics on Venus , heat is mainly lost by conduction through the lithosphere . This causes enormous lava flows, accounting for 80% of Venus' surface area. Many of the mountains are large shield volcanoes that range in size from 150–400 km (95–250 mi) in diameter and 2–4 km (1.2–2.5 mi) high. More than 80 of these large shield volcanoes have summit calderas averaging 60 km (37 mi) across. Io, unusually,

2555-573: The air, including large trees. Pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora , and affecting a total area on land of about 874 km (337 sq mi). A moderate-sized tsunami struck the shores of various islands in the Indonesian archipelago on 10 April, with a height of up to 4 m (13 ft) in Sanggar around 22:00. A tsunami of 1–2 m (3–7 ft) in height

2628-411: The base of large impact craters. Also, eruptions may have taken place due to a magma reservoir at the base of the crust. This forms a dome, possibly the same morphology of a shield volcano where calderas universally are known to form. Although caldera-like structures are rare on the Moon, they are not completely absent. The Compton-Belkovich Volcanic Complex on the far side of the Moon is thought to be

2701-577: The caldera atop Fernandina Island collapsed in 1968 when parts of the caldera floor dropped 350 metres (1,150 ft). Since the early 1960s, it has been known that volcanism has occurred on other planets and moons in the Solar System . Through the use of crewed and uncrewed spacecraft, volcanism has been discovered on Venus , Mars , the Moon , and Io , a satellite of Jupiter . None of these worlds have plate tectonics , which contributes approximately 60% of

2774-436: The clouds had dissipated. There were documented fluctuations of cloud cover for various locations that suggested it was a nightly occurrence and the sun killed them off, much like a fog. The class boundaries between 1810 and 1830 without volcanically perturbed years was around 7.9 °C (14.2 °F). In contrast, the volcanically perturbed years (1815–1817) had a change of only around 2.3 °C (4.1 °F). This meant that

2847-508: The cold decade (1810–1819), and the results have been puzzling. The sulfate concentrations found in both Siple Station , Antarctica and central Greenland bounced from 5.0 in January 1816 to 1.1 in August 1818. This means that 25–30 teragrams of sulfur were ejected into the atmosphere, most of which came from Tambora, followed by a rapid decrease through natural processes. Tambora caused the largest shift in sulfur concentrations in ice cores for

2920-664: The collapsed magma chamber, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at the Valles Caldera , Lake Toba , the San Juan volcanic field, Cerro Galán , Yellowstone , and many other calderas. Because a silicic caldera may erupt hundreds or even thousands of cubic kilometers of material in a single event, it can cause catastrophic environmental effects. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and

2993-434: The eruptions intensified. Three plumes rose up and merged. The whole mountain was turned into a flowing mass of "liquid fire". Pumice stones of up to 20 cm (8 in) in diameter started to rain down around 20:00, followed by ash at around 21:00–22:00. Soon after, a violent whirlwind ensued, which hit the village of Saugur (now Sangar), blowing down nearly every house and carrying everything it encountered into

Blake River Megacaldera Complex - Misplaced Pages Continue

3066-406: The evening of 5 April, they were noticed in every quarter, and continued at intervals until the following day. The noise was, in the first instance, almost universally attributed to distant cannon; so much so, that a detachment of troops was marched from Djocjocarta , in the belief that a neighbouring post was being attacked, and along with the coast, boats were in two instances dispatched in quest of

3139-412: The explosion, Mount Tambora's peak elevation was about 4,300 m (14,100 ft), making it one of the tallest peaks in the Indonesian archipelago. After the explosion, its peak elevation had dropped to only 2,851 m (9,354 ft), about two-thirds of its previous height. The 1815 Tambora eruption is the largest observed eruption in recorded history, as shown in the table below. The explosion

3212-463: The food industry. The length of the growing seasons in parts of Massachusetts and New Hampshire were less than 80 days in 1816, resulting in harvest failures (Oppenheimer 2003). Visually unique sunsets were observed in western Europe, and red fog was observed along the eastern coast of the U.S. These unique atmospheric conditions persisted for the better part of 2.5 years.(Robock 2000) Scientists have used ice cores to monitor atmospheric gases during

3285-852: The globe, creating optical phenomena. Prolonged and brilliantly coloured sunsets and twilights were seen frequently in London between 28 June and 2 July 1815 and 3 September and 7 October 1815. The glow of the twilight sky typically appeared orange or red near the horizon and purple or pink above. The estimated number of deaths varies depending on the source. Zollinger (1855) puts the number of direct deaths at 10,000, probably caused by pyroclastic flows. On Sumbawa, 18,000 starved to death or died of disease. About 10,000 people on Lombok died from disease and hunger. Petroeschevsky (1949) estimated that about 48,000 people were killed on Sumbawa and 44,000 on Lombok. Stothers in 1984 and several other authors have accepted Petroeschevsky's claim of 88,000 deaths in total. However,

3358-463: The human species was reduced to approximately 5,000–10,000 people. There is no direct evidence, however, that either theory is correct, and there is no evidence for any other animal decline or extinction, even in environmentally sensitive species. There is evidence that human habitation continued in India after the eruption. Some volcanoes, such as the large shield volcanoes Kīlauea and Mauna Loa on

3431-429: The island of Hawaii , form calderas in a different fashion. The magma feeding these volcanoes is basalt , which is silica poor. As a result, the magma is much less viscous than the magma of a rhyolitic volcano, and the magma chamber is drained by large lava flows rather than by explosive events. The resulting calderas are also known as subsidence calderas and can form more gradually than explosive calderas. For instance,

3504-479: The landscape, and then the Caldera de Taburiente on La Palma . A collapse is triggered by the emptying of the magma chamber beneath the volcano, sometimes as the result of a large explosive volcanic eruption (see Tambora in 1815), but also during effusive eruptions on the flanks of a volcano (see Piton de la Fournaise in 2007) or in a connected fissure system (see Bárðarbunga in 2014–2015). If enough magma

3577-561: The magma to produce a mixture of volcanic ash and other tephra with the very hot gases. The mixture of ash and volcanic gases initially rises into the atmosphere as an eruption column . However, as the volume of erupted material increases, the eruption column is unable to entrain enough air to remain buoyant, and the eruption column collapses into a tephra fountain that falls back to the surface to form pyroclastic flows . Eruptions of this type can spread ash over vast areas, so that ash flow tuffs emplaced by silicic caldera eruptions are

3650-712: The mean annual cycle in 1816 was more linear than bell shaped and 1817 endured cooling across the board. Southeastern England, northern France, and the Netherlands experienced the greatest amount of cooling in Europe, accompanied by New York, New Hampshire, Delaware , and Rhode Island in North America. The documented rainfall was as much as 80 percent more than the calculated normal with regards to 1816, with unusually high amounts of snow in Switzerland, France, Germany, and Poland. This

3723-418: The mountain collapsed to form a caldera, reducing the height of the summit by a third. Around 100 km (24 cu mi) of rock was blasted into the air.(Williams 2012) Toxic gases also were pumped into the atmosphere, including sulfur that caused lung infections.(Cole-Dai et al. 2009) Volcanic ash was over 100 cm (40 in) deep within 75 km (45 mi) of the eruption, while areas within

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3796-468: The northern spring and summer of 1815, a persistent "dry fog" was observed in the northeastern United States. The fog reddened and dimmed the sunlight, such that sunspots were visible to the naked eye. Neither wind nor rainfall dispersed the "fog". It was identified as a stratospheric sulfate aerosol veil. In summer 1816, countries in the Northern Hemisphere suffered extreme weather conditions, dubbed

3869-468: The only volcanic product with volumes rivaling those of flood basalts . For example, when Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km of material (as measured in dense rock equivalent (DRE)), covering a substantial part of North America in up to two metres of debris. Eruptions forming even larger calderas are known, such as the La Garita Caldera in

3942-434: The past 5,000 years. Estimates of the sulfur yield vary from 10 teragrams (Black et al. 2012) to 120 teragrams,(Stothers 2000) with the average of the estimates being 25–30 teragrams. The high concentrations of sulfur could have caused a four-year stratospheric warming of around 15 °C (27 °F), resulting in a delayed cooling of surface temperatures that lasted for nine years.(Cole-Dai et al. 2009) This has been dubbed

4015-462: The ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. The total area that collapses may be hundreds of square kilometers. Some calderas are known to host rich ore deposits . Metal-rich fluids can circulate through the caldera, forming hydrothermal ore deposits of metals such as lead, silver, gold, mercury, lithium, and uranium. One of

4088-570: The road side the remains of several corpses, and the marks of where many others had been interred: the villages almost entirely deserted and the houses fallen down, the surviving inhabitants having dispersed in search of food. ... Since the eruption, a violent diarrhoea has prevailed in Bima, Dompo, and Sang'ir , which has carried off a great number of people. It is supposed by the natives to have been caused by drinking water which has been impregnated with ashes; and horses have also died, in great numbers, from

4161-593: The severity of typhus epidemics in southeast Europe and along the eastern Mediterranean Sea between 1816 and 1819. The climate changes disrupted the Indian monsoons , caused three failed harvests and famine, and contributed to the spread of a new strain of cholera that originated in Bengal in 1816. Many livestock died in New England during the winter of 1816–1817. Cool temperatures and heavy rains resulted in failed harvests in

4234-453: The snow cover in Cabot, Vermont was reported still to be 46 cm (18 in) deep. Such conditions occurred for at least three months and ruined most agricultural crops in North America. Canada experienced extreme cold during that summer. Snow 30 cm (12 in) deep accumulated near Quebec City from 6 to 10 June 1816. The second-coldest year in the Northern Hemisphere since around 1400

4307-532: The spring. The food shortages were compounded by the Napoleonic wars , floods, and cholera. The ash in the atmosphere for several months after the eruption reflected significant amounts of solar radiation, causing unseasonably cool summers that contributed to food shortages. China, Europe, and North America had well-documented below normal temperatures, which devastated their harvests. The monsoon season in China and India

4380-412: The stratosphere, causing a global climate anomaly. Different methods have estimated the ejected sulfur mass during the eruption: the petrological method; an optical depth measurement based on anatomical observations; and the polar ice core sulfate concentration method, using cores from Greenland and Antarctica . The figures vary depending on the method, ranging from 10 to 120 million tonnes . In

4453-541: The thousands of volcanic eruptions that occur over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. Only eight caldera-forming collapses are known to have occurred between 1911 and 2018, with a caldera collapse at Kīlauea , Hawaii in 2018. Volcanoes that have formed a caldera are sometimes described as "caldera volcanoes". The term caldera comes from Spanish caldera , and Latin caldaria , meaning "cooking pot". In some texts

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4526-599: The title "Year without a Summer". The winter months of 1816 were not much different from previous years, but the spring and summer maintained the cool-to-freezing temperatures. The winter of 1817, however, was radically different, with temperatures below −34 °C (−30 °F) in central and northern New York, which were cold enough to freeze lakes and rivers that were normally used to transport supplies. Both Europe and North America suffered from freezes lasting well into June, with snow accumulating to 32 cm (13 in) in August, which killed recently planted crops and crippled

4599-633: The world's best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario , Canada, which formed during the Neoarchean era about 2.7 billion years ago. In the San Juan volcanic field , ore veins were emplaced in fractures associated with several calderas, with the greatest mineralization taking place near the youngest and most silicic intrusions associated with each caldera. Explosive caldera eruptions are produced by

4672-420: The world. Several climate forcings coincided and interacted in a systematic manner that has not been observed after any other large volcanic eruption since the early Stone Age . Mount Tambora experienced several centuries of dormancy before 1815, caused by the gradual cooling of hydrous magma in its closed magma chamber. Inside the chamber at depths between 1.5 and 4.5 km (5,000 and 15,000 ft),

4745-610: Was 11,000 deaths from direct volcanic effects and 49,000 by post-eruption famine and epidemic diseases. Oppenheimer wrote that there were at least 71,000 deaths in total. Reid has estimated that 100,000 people on Sumbawa, Bali, and other locations died from the direct and indirect effects of the eruption. The eruption caused a volcanic winter . During the Northern Hemisphere summer of 1816, global temperatures cooled by 0.53 °C (0.95 °F). This cooling directly or indirectly caused 90,000 deaths. The eruption of Mount Tambora

4818-450: Was 1816, and the 1810s are the coldest decade on record. That was the consequence of Tambora's 1815 eruption and possibly another VEI-6 eruption in late 1808 . The surface temperature anomalies during the summer of 1816, 1817, and 1818 were −0.51 °C (−0.92 °F), −0.44 °C (−0.79 °F), and −0.29 °C (−0.52 °F), respectively. Parts of Europe also experienced a stormier winter. This climate anomaly has been blamed for

4891-515: Was altered, causing flooding in the Yangtze Valley and forcing thousands of Chinese to flee coastal areas. (Granados et al. 2012) The gases also reflected some of the already-decreased incoming solar radiation, causing a 0.4 to 0.7 °C (0.7 to 1.3 °F) decrease in global temperatures throughout the decade. An ice dam formed in Switzerland during the summers of 1816 and 1817, earning 1816

4964-526: Was considered to be part of the 1815 eruption. This eruption was recorded at 2 on the VEI scale. The eruption column reached the stratosphere at an altitude of more than 43 km (141,000 ft). The coarser ash particles settled out one to two weeks after the eruptions, but the finer ash particles stayed in the atmosphere from a few months to a few years at altitudes of 10–30 km (33,000–98,000 ft). Longitudinal winds spread these fine particles around

5037-402: Was heard at least 2,600 km (1,600 mi) away and possibly over 3350 km (2060 mi) away, and ash fell at least 1,300 km (810 mi) away. On my trip towards the western part of the island, I passed through nearly the whole of Dompo and a considerable part of Bima . The extreme misery to which the inhabitants have been reduced is shocking to behold. There were still on

5110-578: Was reported in Besuki, East Java, before midnight, and one of 2 m (7 ft) in height in the Molucca Islands . The total death toll has been estimated to be around 4,600. Loud explosions were heard until the next evening, 11 April. The ash veil spread as far as West Java and South Sulawesi . A nitrous odor was noticeable in Batavia, and heavy tephra -tinged rain fell, finally receding between 11 and 17 April. The first explosions were heard on this Island in

5183-447: Was the largest cause of this climate anomaly. While there were other eruptions in 1815, Tambora is classified as a VEI-7 eruption with a column 45 km (148,000 ft) tall, eclipsing all others by at least one order of magnitude. The VEI is used to quantify the amount of ejected material, with a VEI-7 being 100 km (24 cu mi). Every index value below that is one order of magnitude (meaning ten times) less. Furthermore,

5256-464: Was the largest known eruption during the ongoing Quaternary period (the last 2.6 million years) and the largest known explosive eruption during the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000–20,000 individuals, resulting in a population bottleneck . More recently, Lynn Jorde and Henry Harpending proposed that

5329-402: Was the worst famine of the 19th century. Volcanism affects the atmosphere in two distinct ways: short-term cooling caused by reflected insolation and long-term warming from increased CO 2 levels. Most of the water vapor and CO 2 is collected in clouds within a few weeks to months because both are already present in large quantities, so the effects are limited. It has been suggested that

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