71-503: Mount Arayat is an isolated potentially active stratovolcano in the Central Luzon plains. Located within vast agricultural lands of Pampanga , it rises prominently to a height of 1,033 metres (3,389 ft) above sea level. Its southern half lies within the municipality of Arayat , while its north half and summit lies within Magalang . Ten miles (16 km) to the west of Mount Arayat
142-747: 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
213-459: A basaltic magma must crystallize specific minerals that are then removed from the melt. This removal can take place in a variety of ways, but most commonly this occurs by crystal settling. The first minerals to crystallize and be removed from a basaltic parent are olivines and amphiboles . These mafic minerals settle out of the magma, forming mafic cumulates. There is geophysical evidence from several arcs that large layers of mafic cumulates lie at
284-474: 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
355-515: 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
426-713: A law declaring Mount Arayat as a protected landscape under the National Integrated Protected Areas System . 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 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
497-739: 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
568-461: 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 ,
639-678: A similar time to reach the peak, however, this route takes you through the Arayat Amphitheatre and the so-called White Rock which legend claims to be the Home of Apung/Aring Sinukuan. There are two other trails on Mount Arayat's slopes as of 2017: the Pinnacle, which is a knife edge monkey trail, and the TKO, which is the hardest trail. The trails in San Juan Banyo, Arayat Pampanga. However, these two features,
710-509: A smaller andesitic dome in the collapse amphitheater. There are historical records of eruption in Arayat and the only dated rocks are 530- and 650-thousand-year-old basalts predating the collapse and formation of the lava dome . However, weak steaming is currently present in some of the heavily eroded vents on the North Western side of the summit. Additionally an analysis report indicates that
781-518: A subducting slab generates magma resembling high-magnesium andesites. Notable stonemasonry structures built with andesite include: In 2009, researchers revealed that andesite was found in two meteorites (numbered GRA 06128 and GRA 06129) that were discovered in the Graves Nunataks icefield during the US Antarctic Search for Meteorites 2006/2007 field season. This possibly points to
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#1732858645053852-411: Is Angeles City and the former Clark Air Base . The active volcano Mount Pinatubo is located 26 km (16 mi) west, while Manila is located 75 km (47 mi) to the south. Mount Arayat was officially declared a national park in 1933 and a tourist spot in 1997. The mountain is currently under an immense deforestation threat. Mount Arayat has a breached crater on its northwest side with
923-435: Is a volcanic rock of intermediate composition . In a general sense, it is the intermediate type between silica -poor basalt and silica-rich rhyolite . It is fine-grained ( aphanitic ) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende . Andesite is the extrusive equivalent of plutonic diorite . Characteristic of subduction zones, andesite represents
994-527: 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
1065-532: Is believed to either be when he responds to the attack of Namalyari on Mount Pinatubo's 1991 eruption or when the time to call his servants upon the end of the world has come. Prior to Spanish colonization, Sinukuan was known as a powerful male Kapampangan god, named Aring Sinukûan, who was in par with the Kapampangan god of Pinatubo, Apûng Malyari. The two were the second most powerful deities in Kapampangan mythology, next only to Mangechay (sometimes called Mangacha),
1136-462: Is intermediate in its content of silica and low in alkali metals . It has less than 20% quartz and 10% feldspathoid by volume, with at least 65% of the feldspar in the rock consisting of plagioclase . This places andesite in the basalt /andesite field of the QAPF diagram . Andesite is further distinguished from basalt by its silica content of over 52%. However, it is often not possible to determine
1207-533: Is not a distinct rock type in the QAPF classification. Andesite is usually light to dark grey in colour, due to its content of hornblende or pyroxene minerals. but can exhibit a wide range of shading. Darker andesite can be challenging to distinguish from basalt, but a common rule of thumb , used away from the laboratory, is that andesite has a color index less than 35. The plagioclase in andesite varies widely in sodium content, from anorthite to oligoclase , but
1278-476: 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 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
1349-509: Is said to live at the White rock, a Lava dome possibly formed by the last eruption, where its glimmering properties were most likely to have inspired the legend. Contrary to reality, the mountain is believed to be several mountains merging at the center including the tallest two peaks. Sinukuan is believed to have daughters who come down only during time of grace and are disguised as humans, Sinukuan himself can be disguised as human. The day he comes back
1420-514: Is so characteristic of the Earth's unique plate tectonics that the Earth has been described as an "andesite planet". During subduction, the subducted oceanic crust is subjected to increasing pressure and temperature, leading to metamorphism . Hydrous minerals such as amphibole , zeolites , or chlorite (which are present in the oceanic lithosphere ) dehydrate as they change to more stable, anhydrous forms, releasing water and soluble elements into
1491-451: 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
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#17328586450531562-433: Is the principal phenocryst mineral, the andesite will be described as a hornblende andesite . Andesite lava typically has a viscosity of 3.5 × 10 cP (3.5 × 10 Pa⋅s) at 1,200 °C (2,190 °F). This is slightly greater than the viscosity of smooth peanut butter . As a result, andesitic volcanism is often explosive, forming tuffs and agglomerates . Andesite vents tend to build up composite volcanoes rather than
1633-447: Is typically andesine , in which anorthite makes up about 40 mol% of the plagioclase. The pyroxene minerals that may be present include augite , pigeonite , or orthopyroxene . Magnetite , zircon , apatite , ilmenite , biotite , and garnet are common accessory minerals. Alkali feldspar may be present in minor amounts. Andesite is usually porphyritic , containing larger crystals ( phenocrysts ) of plagioclase formed prior to
1704-450: 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
1775-403: 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
1846-500: The Andes , magma often pools in the shallow crust creating magma chambers. Magmas in these reservoirs become evolved in composition (dacitic to rhyolitic) through both the process of fractional crystallization and partial melting of the surrounding country rock . Over time as crystallization continues and the system loses heat, these reservoirs cool. In order to remain active, magma chambers must have continued recharge of hot basaltic melt into
1917-800: 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
1988-573: 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
2059-891: 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
2130-443: 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
2201-442: The shield volcanoes characteristic of basalt, with its much lower viscosity resulting from its lower silica content and higher eruption temperature. Block lava flows are typical of andesitic lavas from composite volcanoes. They behave in a similar manner to ʻaʻā flows but their more viscous nature causes the surface to be covered in smooth-sided angular fragments (blocks) of solidified lava instead of clinkers. As with ʻaʻā flows,
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2272-607: 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
2343-481: 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
2414-585: 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
2485-415: The 984-metre (3,228 ft) Pinnacle Peak is located on the southeast crater rim. Post-collapse activity formed an andesitic lava dome known as White Rock in the collapse amphitheater. There are no cultural records of historical eruptions. However, weak steaming is currently present in some of the heavily eroded vents on the North Western side of the summit. The ancient eruptions were said to have caused
2556-457: The Pinnacle and TKO, cannot be considered peaks because they are not prominent unlike the North and South peak, and thus are only considered as view decks as per International Mountaineering definitions. The Mountain is said to be the home of the god/sorcerer named Sinukuan/Sinukwan or Sucu, which could mean "The end" or "he to whom others have surrendered." The mountain was said to have been located in
2627-717: The Spanish added 'Maria' to Sinukuan's name to somewhat turn her into Catholic in a bid to further subjugate the natives and convert them into Roman Catholicism. In recent years, locals have cited that there is a man in the mountain, angry due to the deforestation that was happening. Others say that it was Aring Sinukuan. Fumarole activity is reported on the NW side of the summit. The Global Volcanism Program lists Mount Arayat as Holocene Philippine Institute of Volcanology and Seismology (PHIVOLCS), list Mount Arayat as Potentially active volcano. In April 2022, President Rodrigo Duterte signed
2698-439: The afternoon. He also had a winged assistant named Galurâ, a giant eagle deity believed to be the bringer of storms, and a wife named Mingan. However, when the Spanish arrived, they 'rebranded' Sinukuan as a woman, thinking that the people would not revere the deity if he was a female, not knowing that the great elder deity of the Kapampangan was a woman named Mangechay. Despite this, the natives continued to revere Sinukuan. Furious,
2769-816: 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
2840-741: 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
2911-408: The base of the crust. Once these mafic minerals have been removed, the melt no longer has a basaltic composition. The silica content of the residual melt is enriched relative to the starting composition. The iron and magnesium contents are depleted. As this process continues, the melt becomes more and more evolved eventually becoming andesitic. Without continued addition of mafic material, however,
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2982-473: The control of his forces. Several engagements would occur here afterwards until his surrender on January 15, 1898. On Mount Arayat, Colonel Thorpe, an American guerrilla officer, was captured by Japanese forces on December 10, 1942. Mount Arayat would then be used as a hiding place for communist Filipino guerrillas called the Hukbalahap afterwards. Nicanor Songco "Bapa" developed a plan on how they could spread
3053-496: The crater collapse and formation of the lava dome known as White Rock, which could have occurred in the last 2000 years. The mountain which is believed to be several peaks merged at the top by some local people is actually a Single-Cone Stratovolcano . Two trails lead to the peaks of Mount Arayat. Mount Arayat National Park Located at San Juan Baño in Arayat, Pampanga has a trail to the southern Peak, taking around 3–4 hours to reach
3124-495: The dominant rock type in island arcs . The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust . The name andesite is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that
3195-431: The extrusion that brought the magma to the surface, embedded in a finer-grained matrix . Phenocrysts of pyroxene or hornblende are also common. These minerals have the highest melting temperatures of the typical minerals that can crystallize from the melt and are therefore the first to form solid crystals. Classification of andesites may be refined according to the most abundant phenocryst . For example, if hornblende
3266-540: 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
3337-462: The formation of a Lava Dome on the Western Slopes of the mountain known as White Rock which makes a nice tourist destination and is usually a field trip destination for students of Pampanga State Agricultural University. The Arayat amphitheatre is said to have been caused by the summit's collapse on the western side but a much deeper crater is present on the eastern side, it was said that the mountain
3408-412: The great elder and creator goddess. Aring Sinukûan was the sun god of war and death, taught the early inhabitants the industry of metallurgy, wood cutting, rice culture and waging war. He had three children, namely, Munag Sumalâ, the golden serpent god who represent dawn, Lakandanup, the god of gluttony who represented the sun at noon time, and Gatpanapun, the noble god who only knew pleasure and represented
3479-478: 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
3550-458: 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
3621-530: The information of their escape to Mount Arayat to be safe in the height of the war. This plan would be the reason for the survival of their family from Bulacan, Pampanga and Nueva Ecija who joined them at that time. When they found out that the Japanese soldiers had arrived at their place, they quickly left and went to Mount Arayat but when they were about to go up, the officers of the Japanese soldiers came to arrest him. Nicanor surrendered to ensure everyone's safety. He
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#17328586450533692-500: 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
3763-437: The melt will eventually reach a rhyolitic composition. This produces the characteristic basalt-andesite-rhyolite association of island arcs, with andesite the most distinctive rock type. Partially molten basalt in the mantle wedge moves upwards until it reaches the base of the overriding crust. Once there, the basaltic melt can either underplate the crust, creating a layer of molten material at its base, or it can move into
3834-588: The mineral composition of volcanic rocks, due to their very fine grain size, and andesite is then defined chemically as volcanic rock with a content of 57% to 63% silica and not more than about 6% alkali metal oxides. This places the andesite in the O2 field of the TAS classification . Basaltic andesite , with a content of 52% to 57% silica, is represented by the O1 field of the TAS classification but
3905-512: The molten interior of the flow, which is kept insulated by the solidified blocky surface, advances over the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻaʻā flows. Though andesite is common in other tectonic settings, it is particularly characteristic of convergent plate margins . Even before the Plate Tectonics Revolution , geologists had defined an andesite line in
3976-455: The name "Arayat" are multifaceted and have evolved over time. The earliest mention of the mountain's name appears in a 1696 travel diary by Gemelli Careri , where it is noted that the natives referred to the mountain as " Bondo Kalaya ," later becoming " Bondoc Alaya " (literally "Mount Alaya"). This eventually transformed into "Arayat." Several theories exist regarding the name's origin: Additionally, some sources distinguish between "Aláya" as
4047-653: The name of the mountain and "Aráyat" as the name of the town. During the Philippine Revolution , the Filipino revolutionaries retreated on Mount Arayat after the failure of the Cry of Nueva Ecija during September 1896 when the Spanish counter-attacked at San Isidro . In September 1897, Gen. Francisco Macabulos retreated to Mount Arayat along with his men to avoid capture by the Spanish authorities in Tarlac, which used to be under
4118-510: The overlying wedge of mantle. Fluxing water into the wedge lowers the solidus of the mantle material and causes partial melting. Due to the lower density of the partially molten material, it rises through the wedge until it reaches the lower boundary of the overriding plate. Melts generated in the mantle wedge are of basaltic composition, but they have a distinctive enrichment of soluble elements (e.g. potassium (K), barium (Ba), and lead (Pb)) which are contributed from sediment that lies at
4189-441: The overriding plate in the form of dykes . If it underplates the crust, the basalt can (in theory) cause partial melting of the lower crust due to the transfer of heat and volatiles. Models of heat transfer, however, show that arc basalts emplaced at temperatures 1100–1240 °C cannot provide enough heat to melt lower crustal amphibolite . Basalt can, however, melt pelitic upper crustal material. In continental arcs, such as
4260-516: The peak. The Southern Peak offers views of Central Luzon, including a view of Pampanga River . The collapsed western Slope that forms the other half of its caldera-like crater can also be seen. It offers a view of the mountains of Zambales and Bataan (to the west), and the mountains of the Sierra Madre range (to the east). The northern or higher Peak can be accessed on a route from Pampanga State Agricultural University in Magalang, Pampanga , taking
4331-460: 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
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#17328586450534402-455: The swamp to its south but relocated because of the evil ways of those who lived there, in addition to which, the people of the swamp were made to suffer numerous misfortunes. Sinukuan is believed to be able to transform and do as he pleases at will, his only real rival being Namalyari of Mount Pinatubo . The waterfalls at Ayala in Magalang, Pampanga is said to be his bathing quarters, and it is often visited by tourists and natives alike. Sinukuan
4473-541: The system. When this basaltic material mixes with the evolved rhyolitic magma, the composition is returned to andesite, its intermediate phase. Evidence of magma mixing is provided by the presence of phenocrysts in some andesites that are not in chemical equilibrium with the melt in which they are found. High-magnesium andesites ( boninites ) in island arcs may be primitive andesites, generated from metasomatized mantle. Experimental evidence shows that depleted mantle rock exposed to alkali fluids such as might be given off by
4544-585: The top of the subducting plate. Although there is evidence to suggest that the subducting oceanic crust may also melt during this process, the relative contribution of the three components (crust, sediment, and wedge) to the generated basalts is still a matter of debate. Basalt thus formed can contribute to the formation of andesite through fractional crystallization, partial melting of crust, or magma mixing, all of which are discussed next. Intermediate volcanic rocks are created via several processes: To achieve andesitic composition via fractional crystallization ,
4615-536: The volcano erupted over the last 2,000 years, but it is believed to refer to the volcanic activity of the volcano. Mount Arayat is considered mystical in ancient Kapampangan folklore as the legendary home of Aung/Aring Sinukuan/Sinkuan/Suku or the Fairy known as diwata Maria Sinukuan . According to research gathered by Kapampangan students of Henry Otley Beyer , the mountain was the abode of Apung/Aring Sinukuan, rival of Apu Namalyari of Mount Pinatubo . The origins of
4686-481: The western Pacific that separated basalt of the central Pacific from andesite further west. This coincides with the subduction zones at the western boundary of the Pacific Plate . Magmatism in island arc regions comes from the interplay of the subducting plate and the mantle wedge , the wedge-shaped region between the subducting and overriding plates. The presence of convergent margins dominated by andesite
4757-406: The western and part of the northern rim due to erosion. This has resulted in a breached crater which opens in a west-northwest direction. This area is the apparent source of a major debris-avalanche deposit that forms hummocky terrain beyond the west and northwest sides of the volcano. The 1,026-metre (3,366 ft) summit stands on the northeast side of the breached crater, known as North Peak, while
4828-412: 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
4899-465: 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 . Andesitic Andesite ( / ˈ æ n d ə z aɪ t / )
4970-420: Was once a volcanic island, until eruptions covered the surrounding area with soil, eruptions were said to be the possible cause of a theorized re-route of Pampanga River which is said to have once passed on the western side rather than eastern side where it currently moves. Rock types are basalt and andesite . The only rocks reported to have been dated are 0.53 and 0.65 million-year-old basalts. These predate
5041-535: Was tortured by having his skin removed from his arm. Following this, he was released by the Japanese soldiers and he was able to return to Mount Arayat and his family. Mount Arayat stands in the middle of the largely-agricultural 15 to 35 metres (49 to 115 ft) AMSL Central Luzon Plain, serving as a distinct landmark in Pampanga province. The mountain is topped by a circular volcanic crater about 1.2 kilometres (0.75 mi) in diameter, much of which has collapsed on
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