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107-560: Plinian/Vesuvian eruptions are marked by columns of volcanic debris and hot gases ejected high into the stratosphere , the second layer of Earth's atmosphere. The key characteristics are the ejection of a large amount of pumice and very powerful continuous gas-driven eruptions. Short eruptions can end in less than a day, but longer events can continue for several days or months. The longer eruptions begin with production of clouds of volcanic ash, sometimes with pyroclastic surges . The amount of magma ejected can be so large that it depletes

214-458: A phreatic (steam explosion powered) stage that deposited 3 centimetres (1.2 in) of ash over 400 square kilometres (150 sq mi) of northwest Lombok. A magmatic stage followed, and lithic -rich pumice rained down, the fallout reaching a thickness of 8 centimetres (3.1 in) both upwind on East Lombok and on Bali. This was followed by lapilli rock as well as ash fallout, and pyroclastic flows that were partially confined within

321-457: A vesicular texture caused by voids left by volatiles trapped in the molten lava . Pumice is a highly vesicular rock produced in explosive volcanic eruptions . Most modern petrologists classify igneous rocks, including volcanic rocks, by their chemistry when dealing with their origin. The fact that different mineralogies and textures may be developed from the same initial magmas has led petrologists to rely heavily on chemistry to look at

428-404: A better sight of this very uncommon appearance. A cloud, from which mountain was uncertain, at this distance (but it was found afterwards to come from Mount Vesuvius), was ascending, the appearance of which I cannot give you a more exact description of than by likening it to that of a pine tree, for it shot up to a great height in the form of a very tall trunk, which spread itself out at the top into

535-430: A black glassy substance called obsidian . When filled with bubbles of gas, the same lava may form the spongy appearing pumice . Allowed to cool slowly, it forms a light-colored, uniformly solid rock called rhyolite. The lavas, having cooled rapidly in contact with the air or water, are mostly finely crystalline or have at least fine-grained ground-mass representing that part of the viscous semi-crystalline lava flow that

642-662: A catastrophic eruption occurred at Samalas, a volcano on the Indonesian island of Lombok . The event had a probable Volcanic Explosivity Index of 7, making it one of the largest volcanic eruptions during the Holocene epoch . It left behind a large caldera that contains Lake Segara Anak . Later volcanic activity created more volcanic centres in the caldera, including the Barujari cone, which remains active. The event created eruption columns reaching tens of kilometres into

749-410: A close analogy to hot solutions of salts in water, which, when they approach the saturation temperature, first deposit a crop of large, well-formed crystals (labile stage) and subsequently precipitate clouds of smaller less perfect crystalline particles (metastable stage). In igneous rocks the first generation of crystals generally forms before the lava has emerged to the surface, that is to say, during

856-424: A cutoff for an ultra-Plinian eruption. In the criteria of Volcanic Explosivity Index , recognizing an eruption as ultra-Plinian would make it at least VEI-5 or higher. The threshold for ultra-Plinian eruptions is defined by an eruptive column height of 45 km (28 mi), or 41 km (25 mi) more recently. The few instances of eruptions that lie at the transition between Plinian and ultra-Plinian include

963-708: A decade-long thinning of tree rings in Norway and Sweden. Cooling may have lasted for 4–5 years based on simulations and tree ring data. Another effect of the eruption-induced climate change may have been a brief decrease in atmospheric carbon dioxide concentrations. A decrease in the growth rate of atmospheric carbon dioxide concentrations was recorded after the 1992 Pinatubo eruption; several mechanisms for volcanically driven decreases in atmospheric CO 2 concentration have been proposed, including colder oceans absorbing extra CO 2 and releasing less of it, decreased respiration rates leading to carbon accumulation in

1070-662: A geoscientist of the Pantheon-Sorbonne University who had already suspected that a volcano on that island may be responsible, to conclude that the Samalas volcano was this volcano. The role of the Samalas eruption in the global climate events was confirmed by comparing the geochemistry of glass shards found in ice cores to that of the eruption deposits on Lombok. Later, geochemical similarities between tephra found in polar ice cores and eruption products of Samalas reinforced this localization. Ice cores in

1177-459: A good supplier will know what sort of volcanic rock they are selling. The sub-family of rocks that form from volcanic lava are called igneous volcanic rocks (to differentiate them from igneous rocks that form from magma below the surface, called igneous plutonic rocks ). The lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition. If a rhyolite lava-stream cools quickly, it can quickly freeze into

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1284-686: A growth of ice caps and sea ice , and glaciers in the Alps, Bhutan Himalaya , the Pacific Northwest and the Patagonian Andes grew in size. The advances of ice after the Samalas eruption may have strengthened and prolonged the climate effects. Later volcanic activity in 1269, 1278, and 1286 and the effects of sea ice on the North Atlantic would have further contributed to ice expansion. The glacier advances triggered by

1391-609: A man of such learning and research as my uncle extraordinary and worth further looking into. Pliny the Elder set out to rescue the victims from their perilous position on the shore of the Bay of Naples , and launched his galleys , crossing the bay to Stabiae (near the modern town of Castellammare di Stabia). Pliny the Younger provided an account of his death, and suggested that he collapsed and died through inhaling poisonous gases emitted from

1498-462: A paramorph of augite and magnetite, which may partially or completely substitute for the original crystal but still retains its characteristic outlines. The mechanical behaviour of volcanic rocks is complicated by their complex microstructure. For example, attributes such as the partitioning of the void space (pores and microcracks), pore and crystal size and shape, and hydrothermal alteration can all vary widely in volcanic rocks and can all influence

1605-546: A reference to the aftermath of the eruption. Mount Rinjani avalanched and Mount Samalas collapsed, followed by large flows of debris accompanied by the noise coming from boulders. These flows destroyed Pamatan. All houses were destroyed and swept away, floating on the sea, and many people died. During seven days, big earthquakes shook the Earth, stranded in Leneng, dragged by the boulder flows, People escaped and some of them climbed

1712-412: A sort of branches; occasioned, I imagine, either by a sudden gust of air that impelled it, the force of which decreased as it advanced upwards, or the cloud itself being pressed back again by its own weight, expanded in the manner I have mentioned; it appeared sometimes bright and sometimes dark and spotted, according as it was either more or less impregnated with earth and cinders. This phenomenon seemed to

1819-538: A source in a volcano near Greenland had been considered but Icelandic records made no mention of eruptions around 1250 and it was found in 1988 that ice cores in Antarctica —at Byrd Station and the South Pole —also contained sulfate signals. Sulfate spikes were also found in ice cores from Ellesmere Island , Canada, and the Samalas sulfate spikes were used as stratigraphic markers for ice cores even before

1926-583: A temperature of about 1,000 °C (1,830 °F). Its eruption may have been triggered either by the entry of new magma into the magma chamber or the effects of gas bubble buoyancy. The eruption had a Volcanic Explosivity Index of 7, making it one of the largest eruptions of the current epoch, the Holocene. Eruptions of comparable intensity include the Kurile lake eruption (in Kamchatka , Russia) in

2033-520: A tephra layer sampled at Dongdao island in the South China Sea has been tentatively linked to Samalas. Ash and aerosols might have impacted humans and corals at large distances from the eruption. There are several estimates of the volumes expelled during the various stages of the Samalas eruption. The first stage reached a volume of 12.6–13.4 cubic kilometres (3.0–3.2 cu mi). The phreatomagmatic phase has been estimated to have had

2140-520: A time marker in chronostratigraphic studies. Ice cores from Illimani in Bolivia contain thallium and sulfate spikes from the eruption. For comparison, the 1991 eruption of Pinatubo ejected only about a tenth of the amount of sulfur erupted by Samalas. Sulfate deposition from the Samalas eruption has been noted at Svalbard , and the fallout of sulfuric acid from the volcano may have directly affected peatlands in northern Sweden. In addition,

2247-405: A volcanic eruption; one explanation is that climate models tend to assume that aerosol optical depth increases linearly with the quantity of erupted sulfur when in reality self-limiting processes limit its growth. The possible occurrence of an El Niño before the eruption may have further reduced the cooling. The Samalas eruption, together with 14th century cooling, is thought to have set off

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2354-449: A volcanic event, the global spread indicating a tropical volcano as the cause. The suggestion that Samalas/Rinjani might be the source volcano was first raised in 2012, since the other candidate volcanoes— El Chichón and Quilotoa —did not match the chemistry of the sulfur spikes. El Chichon, Quilotoa and Okataina were also inconsistent with the timespan and size of the eruption. All houses were destroyed and swept away, floating on

2461-502: A volcanic rock's origin. The chemical classification of igneous rocks is based first on the total content of silicon and alkali metals ( sodium and potassium ) expressed as weight fraction of silica and alkali oxides ( K 2 O plus Na 2 O ). These place the rock in one of the fields of the TAS diagram . Ultramafic rock and carbonatites have their own specialized classification, but these rarely occur as volcanic rocks. Some fields of

2568-567: A volume of 0.3 cubic kilometres (0.072 cu mi) dense rock equivalent, may have been deposited by an eruption from either Rinjani or Samalas; it is dated to 2,550 ± 50 BP, at the end of the time range during which Rinjani formed. The deposits from this eruption reached thicknesses of 6 centimetres (2.4 in) 28 kilometres (17 mi) away. Additional eruptions by either Rinjani or Samalas are dated 11,980 ± 40, 11,940 ± 40, and 6,250 ± 40 BP. Eruptive activity continued until about 500 years before 1257. Most volcanic activity now occurs at

2675-425: A volume of 0.9–3.5 cubic kilometres (0.22–0.84 cu mi). The total dense rock equivalent volume of the whole eruption was at least 40 cubic kilometres (9.6 cu mi). The magma erupted was trachydacitic and contained amphibole , apatite , clinopyroxene , iron sulfide , orthopyroxene , plagioclase , and titanomagnetite . It formed out of basaltic magma by fractional crystallization and had

2782-403: Is 3 centimetres (1.2 in) thick. Most of the tephra was deposited west-southwest of Samalas. Considering the thickness of Samalas Tephra found at Mount Merapi, the total volume may have reached 32–39 cubic kilometres (7.7–9.4 cu mi). The dispersal index (the surface area covered by an ash or tephra fall) of the eruption reached 7,500 square kilometres (2,900 sq mi) during

2889-401: Is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava , but look as if they were (such as sedimentary limestone with dissolution pitting ). To convey anything about the physical or chemical properties of the rock, a more specific term should be used;

2996-408: Is contentious; Tambora might have produced more sulfur but Samalas may have been more effective at injecting tephra into the stratosphere . After the eruption, it probably took weeks to months for the fallout to reach large distances from the volcano. When large scale volcanic eruptions inject aerosols into the atmosphere, they can form stratospheric veils. These reduce the amount of light reaching

3103-411: Is dependent on two things: the initial composition of the primary magma and the subsequent differentiation. Differentiation of most magmas tends to increase the silica ( SiO 2 ) content, mainly by crystal fractionation . The initial composition of most magmas is basaltic , albeit small differences in initial compositions may result in multiple differentiation series. The most common of these series are

3210-410: Is usually dacitic or rhyolitic , rich in silica. Basaltic , low-silica lavas rarely produce Plinian eruptions unless specific conditions are met (low magma water content <2%, moderate temperature, and rapid crystallization); a recent basaltic example is the 1886 eruption of Mount Tarawera on New Zealand's North Island . Pliny the Younger described the initial observations of his uncle, Pliny

3317-661: The Great Famine of 1315–17 . The price for cereal increased in Britain, France, and Italy, augmented by price speculation . Outbreaks of disease occurred during this time in the Middle East, England and Italy, including typhus . During and after the winter of 1258–59, exceptional weather was reported less commonly, but the winter of 1260–61 was very severe in Iceland, Italy, and elsewhere. The disruption caused by

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3424-529: The Oligocene – Miocene , with old volcanic units cropping out in southern parts of the island. Samalas was built up by volcanic activity before 12,000 BP . Rinjani formed between 11,940 ± 40 and 2,550 ± 50 BP, with an eruption between 5,990 ± 50 and 2,550 ± 50 BP forming the Propok Pumice with a dense rock equivalent volume of 0.1 cubic kilometres (0.024 cu mi). The Rinjani Pumice, with

3531-636: The P3 phase of 1257 Samalas eruption , 1991 eruption of Mount Pinatubo , the Plinian phase of the Campanian Ignimbrite , Tsankawi Pumice Bed of Tshirege Member of Bandelier Tuff , and the 1902 eruption of Santa María . The once unequivocal ultra-Plinian classification of the Hatepe eruption has been called into question, with recent evidence showing that it is an artifact of an unrecognized shift in

3638-441: The biosphere , and increased productivity of the biosphere due to increased scattered sunlight and the fertilization of oceans by volcanic ash. The Samalas signal is only inconsistently reported from tree ring climate information, and the temperature effects were likewise limited, probably because the large sulfate output altered the average size of particles and thus their radiative forcing . Climate modelling indicated that

3745-497: The mantle wedge . Before the eruption, Mount Samalas may have been as tall as 4,200 ± 100 metres (13,780 ± 330 ft), based on reconstructions that extrapolate upwards from the surviving lower slopes, and thus taller than Mount Kinabalu which is presently the highest mountain in tropical Asia; Samalas's current height is less than that of the neighbouring Mount Rinjani, which reaches 3,726 metres (12,224 ft). The oldest geological units on Lombok are from

3852-408: The pyroxenes . Bowen's reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks. Occasionally, a magma may pick up crystals that crystallized from another magma; these crystals are called xenocrysts . Diamonds found in kimberlites are rare but well-known xenocrysts; the kimberlites do not create the diamonds, but pick them up and transport them to

3959-562: The tholeiitic , calc-alkaline , and alkaline . Most volcanic rocks share a number of common minerals . Differentiation of volcanic rocks tends to increase the silica (SiO 2 ) content mainly by fractional crystallization . Thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount of silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite . While still dominated by silicates, more primitive volcanic rocks have mineral assemblages with less silica, such as olivine and

4066-566: The 13th century. The first settlement of New Zealand most likely occurred 1230–1280 AD and the arrival of people there and on other islands in the region may reflect such a climate-induced migration. Contemporary chronicles in Europe mention unusual weather conditions in 1258. Reports from 1258 in France and England indicate a dry fog, giving the impression of a persistent cloud cover to contemporary observers. Medieval chronicles say that in 1258,

4173-777: The 7th millennium BC , the Mount Mazama (United States, Oregon ) eruption in the 6th millennium BC, the Cerro Blanco ( Argentina ) eruption about 4,200 years ago, the Minoan eruption (in Santorini , Greece) between 1627 and 1600 BC, the Tierra Blanca Joven eruption of Lake Ilopango (El Salvador) in the 6th century, and Mt. Tambora in 1815. Such large volcanic eruptions can result in catastrophic impacts on humans and widespread loss of life both close to

4280-498: The Barujari volcano with eruptions in 1884, 1904, 1906, 1909, 1915, 1966, 1994, 2004, and 2009; Rombongan was active in 1944. Volcanic activity mostly consists of explosive eruptions and ash flows. The rocks of the Samalas volcano are mostly dacitic , with a SiO 2 content of 62–63 percent by weight. Volcanic rocks in the Banda arc are mostly calc-alkaline ranging from basalt over andesite to dacite . The crust beneath

4387-427: The Earth's current land surface. Volcanic rocks are usually fine-grained or aphanitic to glass in texture. They often contain clasts of other rocks and phenocrysts . Phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye . Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a very fine grained matrix. Volcanic rocks often have

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4494-403: The Elder , of the 79 AD eruption of Mount Vesuvius : On August 24th, about one in the afternoon, my mother desired him to observe a cloud which appeared of a very unusual size and shape. He had just taken a turn in the sun and, after bathing himself in cold water, and making a light luncheon, gone back to his books: he immediately arose and went out upon a rising ground from whence he might get

4601-696: The Muntilan Tephra, which was found on the slopes of other volcanoes of Java, but could not be linked to eruptions in these volcanic systems. This tephra is now considered to be a product of the 1257 eruption and is thus also known as the Samalas Tephra. It reaches thicknesses of 2–3 centimetres (0.79–1.18 in) on Mount Merapi , 15 centimetres (5.9 in) on Mount Bromo , 22 centimetres (8.7 in) at Ijen and 12–17 centimetres (4.7–6.7 in) on Bali's Agung volcano. In Lake Logung 340 kilometres (210 mi) away from Samalas on Java it

4708-501: The P1 and P3 phases is not known individually, but the two phases combined (not including P2) lasted between 12 and 15 hours. The eruption column reached a height of 39–40 kilometres (24–25 mi) during the first stage (P1), and of 38–43 kilometres (24–27 mi) during the third stage (P3); it was high enough that SO 2 in it and its sulfur isotope ratio was influenced by photolysis at high altitudes. The eruption began with

4815-457: The Samalas caldera. The eruption that formed the caldera was first recognized in 2003, and in 2004 a volume of 10 cubic kilometres (2.4 cu mi) was attributed to this eruption. Early research considered that the caldera-forming eruption occurred between 1210 and 1300. In 2013, Lavigne suggested that the eruption occurred between May and October 1257, resulting in the climate changes of 1258. Several villages on Lombok are constructed on

4922-519: The Samalas eruption are documented on Baffin Island , where the advancing ice killed and then incorporated vegetation, conserving it. Likewise, a change in Arctic Canada from a warm climate phase to a colder one coincides with the Samalas eruption. According to 2003 reconstructions, summer cooling reached 0.69 °C (1.24 °F) in the southern hemisphere and 0.46 °C (0.83 °F) in

5029-402: The Samalas eruption may have reduced global temperatures by approximately 2 °C (3.6 °F), a value largely not replicated by proxy data. Better modelling with a general circulation model that includes a detailed description of the aerosol indicated that the principal temperature anomaly occurred in 1258 and continued until 1261. Climate models tend to overestimate the climate impact of

5136-624: The TAS diagram are further subdivided by the ratio of potassium oxide to sodium oxide. Additional classifications may be made on the basis of other components, such as aluminum or iron content. Volcanic rocks are also broadly divided into subalkaline, alkaline, and peralkaline volcanic rocks. Subalkaline rocks are defined as rocks in which SiO 2 < -3.3539 × 10 × A + 1.2030 × 10 × A - 1.5188 × 10 × A + 8.6096 × 10 × A - 2.1111 × A + 3.9492 × A + 39.0 where both silica and total alkali oxide content (A) are expressed as molar fraction . Because

5243-436: The TAS diagram uses weight fraction and the boundary between alkaline and subalkaline rock is defined in terms of molar fraction, the position of this curve on the TAS diagram is only approximate. Peralkaline volcanic rocks are defined as rocks having Na 2 O + K 2 O > Al 2 O 3 , so that some of the alkali oxides must be present as aegirine or sodic amphibole rather than feldspar . The chemistry of volcanic rocks

5350-428: The ascent from the subterranean depths to the crater of the volcano. It has frequently been verified by observation that freshly emitted lavas contain large crystals borne along in a molten, liquid mass. The large, well-formed, early crystals ( phenocrysts ) are said to be porphyritic ; the smaller crystals of the surrounding matrix or ground-mass belong to the post-effusion stage. More rarely lavas are completely fused at

5457-505: The atmosphere and pyroclastic flows that buried much of Lombok and crossed the sea to reach the neighbouring island of Sumbawa . The flows destroyed human habitations, including the city of Pamatan , which was the capital of a kingdom on Lombok. Ash from the eruption fell as far as 340 kilometres (210 mi) away in Java ; the volcano deposited more than 10 cubic kilometres (2.4 cu mi) of rocks and ash. The aerosols injected into

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5564-464: The atmosphere reduced the solar radiation reaching the Earth's surface, causing a volcanic winter and cooling the atmosphere for several years. This led to famines and crop failures in Europe and elsewhere, although the exact scale of the temperature anomalies and their consequences is still debated. The eruption may have helped trigger the Little Ice Age , a centuries-long cold period during

5671-603: The beginning of the Little Ice Age and the Samalas eruption. Around 1300, settlements in many places of the Pacific relocated, perhaps because of a sea level drop that occurred after 1250, and the 1991 eruption of Pinatubo has been linked to small drops in sea level. Climate change triggered by the Samalas eruption and the beginning of the Little Ice Age may have led to people in Polynesia migrating southwestward in

5778-598: The caldera left by the eruption was estimated to be 10–30 kilometres (6.2–18.6 mi), and the location was estimated to be close to the equator and probably north of it. While at first no clear-cut climate anomaly could be correlated to the 1257 sulfate layers, in 2000 climate phenomena were identified in medieval records of the northern hemisphere that are characteristic for volcanic eruptions. Earlier, climate alterations had been reported from studies of tree rings and climate reconstructions. The deposits showed that climate disturbances reported at that time were due to

5885-807: The caldera. Mount Rinjani has also been volcanically active, forming its own crater, Segara Muncar. Other volcanoes in the region include Agung , Batur , and Bratan , on the island of Bali to the west. Lombok is one of the Lesser Sunda Islands in the Sunda Arc of Indonesia, a subduction zone where the Australian Plate subducts beneath the Eurasian Plate at a rate of 7 centimetres per year (2.8 in/year). The magmas feeding Mount Samalas and Mount Rinjani are likely derived from peridotite rocks beneath Lombok, in

5992-488: The consequences of the Samalas eruption exists. The Babad Lombok describe how villages on Lombok were destroyed during the mid-13th century by ash, gas and lava flows, and two additional documents known as the Babad Sembalun and Babad Suwung may also reference the eruption. They are also—together with other texts—the source of the name "Samalas" while the name "Suwung"—"quiet and without life"—may, in turn, be

6099-520: The context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks . Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces . It has been estimated that volcanic rocks cover about 8% of

6206-433: The crystal. It is clear that after the mineral had crystallized it was partly again dissolved or corroded at some period before the matrix solidified. Corroded phenocrysts of biotite and hornblende are very common in some lavas; they are surrounded by black rims of magnetite mixed with pale green augite. The hornblende or biotite substance has proved unstable at a certain stage of consolidation, and has been replaced by

6313-416: The early 20th century. The time period 1250–1300 was heavily disturbed by volcanic activity from four eruptions in 1230, 1257, 1276 and 1286, and is recorded by a moraine from a glacial advance on Disko Island , although the moraine may indicate a pre-Samalas cold spell. These volcanic disturbances along with positive feedback effects from increased ice may have started the Little Ice Age even without

6420-650: The early flowering of violets according to reports from the Kingdom of France , European summers were colder after the eruption, and winters were long and cold. The Samalas eruption came after the Medieval Climate Anomaly , a period early in the last millennium with unusually warm temperatures, and at a time when a period of climate stability was ending, with earlier eruptions in 1108, 1171, and 1230 already having upset global climate. Subsequent time periods displayed increased volcanic activity until

6527-410: The eruption although it is possible that the population of Lombok fled before the eruption. In Bali the number of inscriptions dropped off after the eruption, and Bali and Lombok may have been depopulated by it, possibly for generations, allowing King Kertanegara of Singhasari on Java to conquer Bali in 1284 with little resistance. It might have taken about a century for Lombok to recover from

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6634-409: The eruption and supplied its phreatomagmatic phase with 0.1–0.3 cubic kilometres (0.024–0.072 cu mi) of water. Alternatively, the water could have been supplied by aquifers . Approximately 2.1–2.9 cubic kilometres (0.50–0.70 cu mi) of rock from Rinjani fell into the caldera, a collapse that was witnessed by humans and left a collapse structure that cuts into Rinjani's slopes facing

6741-448: The eruption column and thus would not have entered the stratosphere, the quantities that have been modelled for the Samalas halogen release (227 ± 18 million tonnes of chlorine and up to 1.3 ± 0.3 million tonnes of bromine) would have reduced stratospheric ozone< although only a small portion of the halogens would have reached the stratosphere. One hypothesis is that the resulting increase in ultraviolet radiation on

6848-570: The eruption may have influenced the onset of the Mudéjar revolt of 1264–1266 in Iberia . Swollen and rotting in groups of five or six, the dead lay abandoned in pigsties, on dunghills, and in the muddy streets. Matthew Paris , chronicler of St. Albans A famine in London has been linked to this event; this food crisis was not extraordinary and there were issues with harvests already before

6955-627: The eruption may have interrupted a prolonged drought period. The climate effect in Alaska may have been moderated by the nearby ocean. In 1259, Western Europe and the west coastal North America had mild weather and there is no evidence for summer precipitation changes in Central Europe . Tree rings do not show much evidence of precipitation changes. The eruption led to global disaster in 1257–1258. Very large volcanic eruptions can cause significant human hardship, including famine, away from

7062-653: The eruption might have been somewhat smaller and richer in sulfur. The volcano responsible was thought to be located in the Ring of Fire but could not be identified at first; Tofua volcano in Tonga was proposed at first but dismissed, as the Tofua eruption was too small to generate the 1257 sulfate spikes. A volcanic eruption in 1256 at Harrat al-Rahat near Medina was also too small to trigger these events. Other proposals included several simultaneous eruptions. The diameter of

7169-496: The eruption. The famine occurred at a time of political crisis between King Henry III of England and the English magnates . Witnesses reported a death toll of 15,000 to 20,000 in London. A mass burial of famine victims was found in the 1990s in the centre of London. Matthew Paris of St Albans described how until mid-August 1258, the weather alternated between cold and strong rain, causing high mortality. The resulting famine

7276-596: The eruption. The western coast of Sumbawa was depopulated and remains so to this day; presumably the local populace viewed the area devastated by the eruption as "forbidden" and this memory persisted until recent times. Historical events in Oceania are usually poorly dated, making it difficult to assess the timing and role of specific events, but there is evidence that between 1250 and 1300 there were crises in Oceania, for example at Easter Island , which may be linked with

7383-632: The event and recorded it on the Babad Lombok , a document written on palm leaves . Samalas (also known as Rinjani Tua ) was part of what is now the Rinjani volcanic complex, on Lombok, in Indonesia. The remains of the volcano form the Segara Anak caldera, with Mount Rinjani at its eastern edge. Since the destruction of Samalas, two new volcanoes, Rombongan and Barujari, have formed in

7490-426: The first stage and 110,500 square kilometres (42,700 sq mi) during the third stage, implying that these were a Plinian eruption and an Ultraplinian eruption respectively. Pumice falls with a fine graining and creamy colour from the Samalas eruption have been used as a tephrochronological marker on Bali. Tephra from the volcano was found in ice cores as far as 13,500 kilometres (8,400 mi) away, and

7597-412: The geography of Lombok; they and sediments eroded from the Samalas deposits extended the shorelines of the island and buried river valleys ; a new river network developed on the volcanic deposits after the eruption. Volcanic rocks ejected by the eruption covered Bali and Lombok and parts of Sumbawa. Tephra in the form of layers of fine ash from the eruption fell as far away as Java, forming part of

7704-404: The ground-mass . Microscopic examination of the phenocrysts often reveals that they have had a complex history. Very frequently they show layers of different composition, indicated by variations in color or other optical properties; thus augite may be green in the center surrounded by various shades of brown; or they may be pale green centrally and darker green with strong pleochroism (aegirine) at

7811-735: The growth season ), light tree rings in Canada and northwestern Siberia from 1258 and 1259 respectively, thin tree rings in the Sierra Nevada , California, U.S. cooling in sea surface temperature records off the Korean Peninsula and in lake sediments of northeastern China, a very wet monsoon in Vietnam, droughts in many places in the Northern Hemisphere as well as in southern Thailand cave records, and

7918-505: The hills. The city of Pamatan, capital of a kingdom on Lombok, was destroyed, and both disappeared from the historical record. The royal family survived the disaster according to the Javanese text, which also mentions reconstruction and recovery efforts after the eruption, and there is no clear-cut evidence that the kingdom itself was destroyed by the eruption, as the history there is poorly known in general. Thousands of people died during

8025-402: The island incinerating the island's vegetation. Interaction between these flows and the air triggered the formation of additional eruption clouds and secondary pyroclastic flows. Where the flows entered the sea north and east of Lombok, steam explosions created pumice cones on the beaches and additional secondary pyroclastic flows. Pyroclastic flows descended the northern slopes of Samalas; on

8132-401: The last thousand years. Before the site of the eruption was known, an examination of ice cores around the world had detected a large spike in sulfate deposition from around 1257 providing strong evidence of a large volcanic eruption occurring at that time. In 2013, scientists linked the historical records about Mount Samalas to these spikes. These records were written by people who witnessed

8239-465: The lava with water, so this eruption phase was probably phreatomagmatic . It was followed by three pumice fallout episodes, with deposits over an area wider than was reached by any of the other eruption phases. These pumices fell up to 61 kilometres (38 mi) to the east, against the prevailing wind, in Sumbawa, where they are up to 7 centimetres (2.8 in) thick. The deposition of these pumices

8346-544: The magma chamber below, causing the top of the volcano to collapse, resulting in a caldera . Fine ash and pulverized pumice can be deposited over large areas. Plinian eruptions are often accompanied by loud sounds. The sudden discharge of electrical charges accumulated in the air around the ascending column of volcanic ashes also often causes lightning strikes, as depicted by the English geologist George Julius Poulett Scrope in his painting of 1822 or observed during 2022 Hunga Tonga–Hunga Ha'apai eruption and tsunami . The lava

8453-446: The mechanical behaviour of volcanic rocks can help us better understand volcanic hazards, such as flank collapse. Volcanic rocks : Subvolcanic rocks : Plutonic rocks : Picrite basalt Peridotite Basalt Diabase (Dolerite) Gabbro Andesite Microdiorite Diorite Dacite Microgranodiorite Granodiorite Rhyolite Microgranite Granite 1257 Samalas eruption In 1257,

8560-714: The moment of ejection; they may then cool to form a non-porphyritic, finely crystalline rock, or if more rapidly chilled may in large part be non-crystalline or glassy (vitreous rocks such as obsidian, tachylyte , pitchstone ). A common feature of glassy rocks is the presence of rounded bodies ( spherulites ), consisting of fine divergent fibres radiating from a center; they consist of imperfect crystals of feldspar, mixed with quartz or tridymite ; similar bodies are often produced artificially in glasses that are allowed to cool slowly. Rarely these spherulites are hollow or consist of concentric shells with spaces between ( lithophysae ). Perlitic structure, also common in glasses, consists of

8667-500: The need for changes in solar radiation, though this theory is not without disagreement. The Samalas eruption in Europe is sometimes used as a chronological marker for the beginning of the Little Ice Age. Other inferred effects of the eruption are: Other regions such as Alaska were mostly unaffected. There is little evidence that tree growth was influenced by cold in what is now the Western United States , where

8774-455: The northern and southern hemisphere display sulfate spikes associated with Samalas. The signal is the strongest in the southern hemisphere over the last 1000 years; one reconstruction even considers it the strongest of the last 2500 years. It is about eight times stronger than that of Krakatau . In the northern hemisphere it is only exceeded by the signal of the destructive 1783/1784 Laki eruption. The ice core sulfate spikes have been used as

8881-449: The northern hemisphere. More recent proxy data indicate that a temperature drop of 0.7 °C (1.3 °F) occurred in 1258 and of 1.2 °C (2.2 °F) in 1259, but with differences between various geographical areas. For comparison, the radiative forcing of Pinatubo's 1991 eruption was about a seventh of that of the Samalas eruption. Sea surface temperatures too decreased by 0.3–2.2 °C (0.54–3.96 °F), triggering changes in

8988-453: The ocean circulations. Ocean temperature and salinity changes may have lasted for a decade. Precipitation and evaporation both decreased, evaporation reduced more than precipitation. Volcanic eruptions can also deliver bromine and chlorine into the stratosphere, where they contribute to the breakdown of ozone through their oxides chlorine monoxide and bromine monoxide . While most bromine and chlorine erupted would have been scavenged by

9095-409: The periphery. In the feldspars the center is usually richer in calcium than the surrounding layers, and successive zones may often be noted, each less calcic than those within it. Phenocrysts of quartz (and of other minerals), instead of sharp, perfect crystalline faces, may show rounded corroded surfaces, with the points blunted and irregular tongue-like projections of the matrix into the substance of

9202-454: The presence of concentric rounded cracks owing to contraction on cooling. The phenocrysts or porphyritic minerals are not only larger than those of the ground-mass; as the matrix was still liquid when they formed they were free to take perfect crystalline shapes, without interference by the pressure of adjacent crystals. They seem to have grown rapidly, as they are often filled with enclosures of glassy or finely crystalline material like that of

9309-561: The product of explosive volcanism. They are often felsic (high in silica). Pyroclastic rocks are often the result of volcanic debris, such as ash , bombs and tephra , and other volcanic ejecta . Examples of pyroclastic rocks are tuff and ignimbrite . Shallow intrusions , which possess structure similar to volcanic rather than plutonic rocks, are also considered to be volcanic, shading into subvolcanic . The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava

9416-490: The pyroclastic flow deposits from the 1257 event. A major volcanic event in 1257–1258 was first discovered from data in ice cores; specifically increased sulfate concentrations were found in 1980 within the Crête ice core ( Greenland , drilled in 1974 ) associated with a deposit of rhyolitic ash. The eruption was known as the "mystery eruption". The 1257–1258 layer is the third largest sulfate signal at Crête; at first

9523-478: The resultant mechanical behaviour (e.g., Young's modulus, compressive and tensile strength, and the pressure at which they transition from brittle to ductile behaviour ). As for other crustal rocks, volcanic rocks are brittle and ductile at low and high effective confining pressures, respectively. Brittle behaviour is manifest as faults and fractures, and ductile behaviour can either be distributed (cataclastic pore collapse) or localised (compaction bands). Understanding

9630-524: The sea, and many people died. Babad Lombok The conclusive link between these events and an eruption of Samalas was made in 2013 on the basis of radiocarbon dating of trees on Lombok and the Babad Lombok , a series of writings in Old Javanese on palm leaves that described a catastrophic volcanic event on Lombok which occurred before 1300. These findings induced Franck Lavigne ,

9737-678: The southern slopes they split into two branches that proceeded to the Alas Strait to the east and the Bali Strait to the west. Coral reefs were buried by the pyroclastic flows; some flows crossed the Alas Strait between Sumbawa and Lombok and formed deposits on Sumbawa. These pyroclastic flows reached volumes of 29 cubic kilometres (7.0 cu mi) on Lombok, and thicknesses of 35 metres (115 ft) as far as 25 kilometres (16 mi) from Samalas. The pyroclastic flows altered

9844-407: The sulfate aerosols may have extracted large amounts of the beryllium isotope Be from the stratosphere ; such an extraction event and the subsequent deposition in ice cores may mimic changes in solar activity . The amount of sulfur dioxide released by the eruption has been estimated to be 158 ± 12 million tonnes. Whether the mass release was higher or lower than for Tambora

9951-601: The summer was cold and rainy, causing floods and bad harvests, with cold from February to June. Frost occurred in the summer 1259 according to Russian chronicles. In Europe and the Middle East , changes in atmospheric colours, storms, cold, and severe weather were reported in 1258–1259, with agricultural problems extending to North Africa . In Europe, excess rain, cold and high cloudiness damaged crops and caused famines followed by epidemics , although 1258–1259 did not lead to famines as bad as some other famines such as

10058-620: The surface and cause lower temperatures, which can lead to poor crop yields. Such sulfate aerosols in the case of the Samalas eruption may have remained at high concentrations for about three years according to findings in the Dome C ice core in Antarctica , although a smaller amount may have persisted for an additional time. Other records of the eruption's impact include decreased tree growth in Mongolia between 1258 and 1262 based on tree ring data, frost rings (tree rings damaged by frost during

10165-430: The surface of Earth may have led to widespread immunosuppression in human populations, explaining the onset of epidemics in the years following the eruption. Samalas, along with the 1452/1453 mystery eruption and the 1815 eruption of Mount Tambora , was one of the strongest cooling events in the last millennium, even more so than at the peak of the Little Ice Age. After an early warm winter 1257–1258 resulting in

10272-455: The surface of the Earth. Volcanic rocks are named according to both their chemical composition and texture. Basalt is a very common volcanic rock with low silica content. Rhyolite is a volcanic rock with high silica content. Rhyolite has silica content similar to that of granite while basalt is compositionally equal to gabbro . Intermediate volcanic rocks include andesite , dacite , trachyte , and latite . Pyroclastic rocks are

10379-415: The time it would have taken for its traces to reach the polar ice sheets and be recorded in ice cores and the pattern of tephra deposits. 1257 is the most likely year of the eruption, although a date of 1258 is also possible. The phases of the eruption are also known as P1 (phreatic and magmatic phase), P2 (phreatomagmatic with pyroclastic flows), P3 ( Plinian ) and P4 (pyroclastic flows). The duration of

10486-549: The valleys on Samalas's western flank. Some ash deposits were eroded by the pyroclastic flows, which created furrow structures in the ash. Pyroclastic flows crossed 10 kilometres (6.2 mi) of the Bali Sea , reaching the Gili Islands to the northwest of Samalas and Taliwang east of Lombok, while pumice blocks presumably covered the Alas Strait between Lombok and Sumbawa . The deposits show evidence of interaction of

10593-483: The volcano and at greater distances. The eruption created the 6–7 kilometres (3.7–4.3 mi) wide Segara Anak caldera where the Samalas mountain was formerly located; within its 700–2,800 metres (2,300–9,200 ft) high walls, a 200 metres (660 ft) deep crater lake formed called Lake Segara Anak . The Barujari cone rises 320 metres (1,050 ft) above the water of the lake and has erupted 15 times since 1847. A crater lake may have existed on Samalas before

10700-454: The volcano due to their effect on climate. The social effects are often reduced by the resilience of humans; thus there is often uncertainty about causal links between volcano-induced climate variations and societal changes at the same time. Western and central Indonesia at the time were divided into competing kingdoms that often built temple complexes with inscriptions documenting historical events. However, little direct historical evidence of

10807-527: The volcano is about 20 kilometres (12 mi) thick, and the lower extremity of the Wadati–Benioff zone is about 164 kilometres (102 mi) deep. The events of the 1257 eruption have been reconstructed through geological analysis of the deposits it left and by historical records. The eruption probably occurred during the northern summer in September (uncertainty of 2–3 months) that year, in light of

10914-401: The volcano that caused them was known. The ice cores indicated a large sulfate spike, accompanied by tephra deposition, around 1257–1259, the largest in 7,000 years and twice the size of the spike due to the 1815 eruption of Tambora . In 2003, a dense rock equivalent volume of 200–800 cubic kilometres (48–192 cu mi) was estimated for this eruption, but it was also proposed that

11021-477: The volcano. His body was found interred under the ashes of the eruption with no apparent injuries on 26 August, after the plume had dispersed, confirming asphyxiation or poisoning. In 1980, volcanologist George P. L. Walker proposed Hatepe eruption as the representative of a new class called ultra-Plinian deposits, based on its exceptional dispersive power and eruptive column height. A dispersal index of 50,000 square kilometres (19,000 sq mi) has been proposed as

11128-538: The wind field rather than extreme eruptive vigor. Volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano . Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks . For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In

11235-435: Was followed by another stage of pyroclastic flow activity, probably caused by the collapse of the eruption column that generated the flows. At this time the eruption changed from an eruption-column-generating stage to a fountain-like stage and the caldera began to form. These pyroclastic flows were deflected by the topography of Lombok, filling valleys and moving around obstacles such as older volcanoes as they expanded across

11342-453: Was going on while the mass was still creeping forward under the surface of the Earth, the latest formed minerals (in the ground-mass ) are commonly arranged in subparallel winding lines that follow the direction of movement (fluxion or fluidal structure)—and larger early minerals that previously crystallized may show the same arrangement. Most lavas fall considerably below their original temperatures before emitted. In their behavior, they present

11449-480: Was still liquid at the moment of eruption. At this time they were exposed only to atmospheric pressure, and the steam and other gases, which they contained in great quantity were free to escape; many important modifications arise from this, the most striking being the frequent presence of numerous steam cavities ( vesicular structure) often drawn out to elongated shapes subsequently filled up with minerals by infiltration ( amygdaloidal structure). As crystallization

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