Misplaced Pages

#210789

64-553: Along the western edge of the Ribeirinha Volcano, the Central Volcanic Complex formed about 410,000 years ago, along with several structures that arose from tectonics. Evidence of this process has not been preserved due to subsidence, but it is generally believed that two formations (an Upper and Lower group) reflecting a geochemical variation that occurred about 16,000 years ago. The Lower group (from 410,000 years ago),

128-416: A golden plover ( Pluvialis apricaria ) was nesting on the island, with four eggs. Soon after the island's formation, seals were seen around the island. They soon began basking there, particularly on the northern spit, which grew as the waves eroded the island. Seals were found to be breeding on the island in 1983, and a group of up to 70 made the island their breeding spot. Grey seals are more common on

192-513: A 50% decrease of the resident population of Capelo, and contributed to an increased standard of living, greater working opportunities and some improvements in base incomes. The volcano is a landmark on Faial; its ruined lighthouse and Visitors Center (which lies along the cliff from the volcano) is a tourist destination. A trail network runs from the Visitors Center and lighthouse to the caldera summit. On September 27, 2007, commemorations marking

256-414: A few days the new island, formed mainly of scoria , measured over 500 metres (1,640 feet) in length and had reached a height of 45 metres (148 feet). As the eruptions continued, they became concentrated at one vent along the fissure and began to build the island into a more circular shape. By 24 November, the island measured about 900 by 650 metres (2,950 by 2,130 ft). The violent explosions caused by

320-470: A mound of material that approached sea level, the explosions could no longer be contained, and activity broke the surface. The first noticeable indications of volcanic activity were recorded at the seismic station in Kirkjubæjarklaustur , Iceland from 6 to 8 November 1963, which detected weak tremors emanating from an epicentre approximately west-south-west at a distance of 140 km (87 mi),

384-460: A quarter of the original above-sea-level volume of the island. Its maximum elevation has diminished to 155 m (509 ft). Following the end of the eruption, scientists established a grid of benchmarks against which they measured the change in the shape of the island. In the 20 years following the end of the eruption, measurements revealed that the island was steadily subsiding and had lost about one metre in height. The rate of subsidence

448-517: A second cone was formed. Following a night of torrential rains and ash (on or about 16 November) the explosive activity ceased, and an effusive lava phase began with more ash and explosive rock. By then the largest eruptive column had reached 1450 metres into the air, carrying with it ash from the northwest for a distance of 20 kilometres (6 December). A final pause began on 29 December. Between January and April 1958, new showers of ash and accompanying water vapour (both white and darkened) persisted, and

512-422: A volcanic eruption had begun to breach the surface of the sea. By 11:00 the same day, the eruption column had reached several kilometres in height. At first the eruptions took place at three separate vents along a northeast by southwest trending fissure , but by the afternoon the separate eruption columns had merged into one along the erupting fissure. Over the next week, explosions were continuous, and after just

576-574: Is a small prefabricated hut which is used by researchers while staying on the island. The hut includes a few bunk beds and a solar power source to drive an emergency radio and other key electronics. There is also an abandoned lighthouse foundation. All visitors check themselves and belongings to ensure no seeds are accidentally introduced by humans to the island's developing ecosystem. It is believed that some boys who sneaked over from Heimaey by rowboat planted potatoes, which were promptly dug up once discovered. An improperly managed human defecation resulted in

640-600: Is composed primarily of basaltic rocks, although, less frequently, Hawaiian hawaiitic rocks are observed. Capelinhos is classified a Surtseyan eruption , since it was formed in the relatively shallow coast of the Faial seamount. However, Victor Hugo Forjaz  [ pt ] , a volcanologist and full professor at the University of the Azores , defends that the type of eruption should have been designated as Capelinian as it pre-dates

704-440: Is estimated that Surtsey will remain above sea level until at least the year 2100. The eruption was unexpected, and almost certainly began some days before it became apparent at the surface. The sea floor at the eruption site is 130 metres (430 feet) below sea level, and at this depth volcanic emissions and explosions would be suppressed, quenched and dissipated by the water pressure and density. Gradually, as repeated flows built up

SECTION 10

#1732858331211

768-659: Is located along the Capelo Volcanic Complex, that comprises a western area of fissural volcanism and historical eruptions leading away from the Cabeço do Fogo. The events that began in 1957 were an extension of the volcanic activity that abruptly ended at Costado da Nau, the escarpment at Ponta dos Capelinhos. Similar to the Horta Platform, the peninsula is consistent with the shapes and products resulting from Surtseyan , Strombolian and Hawaiian volcanic types. The formation

832-401: Is the southernmost point of Iceland . It was formed in a volcanic eruption which began 130 metres (430 feet) below sea level, and reached the surface on 14 November 1963. The eruption lasted until 5 June 1967, when the island reached its maximum size of 2.7 km (1.0 sq mi). Since then, wave erosion has caused the island to steadily diminish in size: as of 2012 , its surface area

896-605: The Caldeira Volcano caldera. Although the name "Capelinhos" is associated with the volcano, it technically refers to the western cape of the parish of Capelo . It can be considered the westernmost point of Europe ; there are more westerly islands in the Azores archipelago but they lie on the North American Plate . A volcanic eruption lasted for 13 months, from September 27, 1957 until October 24, 1958, which may have been two overlapping volcanic eruptions. While enlarging

960-455: The Ilha Nova . Arriving on the island, they planted a Portuguese flag, before hurriedly leaving. The New Island had disappeared into the sea by 30 October. On November 4, 1957 a second volcanic event occurred rapidly, forming a second island, and by 12 November 1957 an isthmus had formed linking it with Faial. Explosions and ejecta increased progressively, reaching a climax by 15 December when

1024-727: The 50th anniversary of the eruption and its effects on the island's history and people were broadcast in Portugal and throughout the Azorean diaspora. Surtsey Surtsey (" Surtr 's island" in Icelandic , Icelandic pronunciation: [ˈsʏr̥(t)sˌeiː] ) is an uninhabited volcanic island located in the Vestmannaeyjar archipelago off the southern coast of Iceland . At 63°18′11″N 20°36′18″W  /  63.303°N 20.605°W  / 63.303; -20.605 Surtsey

1088-527: The Capelinhos crater, there were no deaths from the eruption; generally, ash deposits and some projectiles caused the destruction of homes and the blanketing of agricultural lands in the parishes of Capelo and Praia do Norte . A report presented on 15 January 1958 indicated that 164 families had been affected by the eruption. Due to the close relationship between Portugal and the United States, refugees from

1152-738: The Civil Governor, Freitas Pimentel. The Director of the Observatory in Angra , Lieutenant-Colonel José Agostinho overflew the area, and Bernado Almada (at the Prince Albert of Monaco Observatory, in Horta) sent several bulletins relating the increased seismic activity of the area. Between September 16 and 27, 1957, 200 earthquakes of intensity V ( Moderate ) on the Mercalli scale were registered. On September 23,

1216-602: The English abstract of the paper “Fifty years after the Capelinhos eruption we cannot find any tree or bushes on the volcano. In respect of its importance in enhancing understanding of submarine volcanoes, Capelhinos was included by the International Union of Geological Sciences (IUGS) in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The Capelinhos eruption represented

1280-556: The Holy Spirit ) by the locals, 600 meter diameter and 30 meter height with an open crater to the sea. By October 29, the island grew to 99 meters high and 800 meters in diameter of coarse black ash. By the end of the first phase of the eruption, three reporters, Carlos Tudela and Vasco Hogan Teves from public television Rádio e Televisão de Portugal (RTP), journalist Urbano Carrasco (from the newspaper Diário Popular ) and boat pilot Carlos Raulino Peixoto risked their lives by traveling to

1344-430: The activity on the main island diminished, but at the end of May that year an eruption began at a vent 0.6 km (0.37 mi) off the northern shore. By 28 May, an island had appeared, and was named Syrtlingur ( [ˈsɪr̥tliŋkʏr̥] Little Surtsey). The new island was washed away during early June, but reappeared on 14 June. Eruptions at Syrtlingur were much smaller in scale than those that had built Surtsey, with

SECTION 20

#1732858331211

1408-485: The air, causing moderate explosions and accompanied by infra-sonic waves that shook doors and windows on the island and some adjacent islands. This final phase lasted several months: the last lava currents were visible on 21 October, and the last projectiles were reported on 24 October. During this final stage (around 14 May), fumaroles were discovered inside Faial's caldera , that began emitting sulfurous water vapor, boiling clay and mud. Although one person nearly fell into

1472-462: The approximately 490 species found on mainland Iceland. More species continue to arrive, at a typical rate of roughly 2–5 new species per year. The expansion of bird life on the island has both relied on and helped to advance the spread of plant life. Birds use the plants for nesting material, but also continue to assist in the spreading of seeds, and fertilize the soil with their guano . Birds first began nesting on Surtsey three years after

1536-525: The area began to experience the first damages: windows were broken, tiles fell from the roofs. By the next day, the first ash-fall began on land; "in a few hours a black mat covered the extreme West of island...", reaching 2.5 kilometres from the crater, necessitating the evacuation of the settlements of Norte Pequeno and Canto. Initially, gases and pyroclastic explosions persisted until October 13, while gradually diminishing, but were rapidly replaced by violent explosions, lava bombs, ash and lava streaming into

1600-504: The average rate of emission of volcanic materials being about a tenth of the rate at the main vent. Activity was short-lived, continuing until the beginning of October 1965, by which time the islet had an area of 0.15 km (0.058 sq mi). Once the eruptions had ceased, wave erosion rapidly wore the island away, and it disappeared beneath the waves on 24 October. During December 1965, more submarine activity occurred 0.9 km (0.56 mi) southwest of Surtsey, and another island

1664-402: The beleaguered parishes emigrated. The Azorean Refugee Act (September 2, 1958), authorized the emigration of 1,500 people and was sponsored by Democratic Congressmen John O. Pastore of Rhode Island , and a young Senator John F. Kennedy of Massachusetts . In addition to many families from the area of Capelo, other citizens of the Azores benefited from these temporary measures. This resulted in

1728-589: The coast. On September 27, beginning at about 6:45 in the morning, a submarine eruption, 300 m from Ponta dos Capelinhos (100 m from the Ilhéus dos Capelinhos ) began. Whale spotters at Costado da Nau, a few meters above the Capelinhos lighthouse , saw the ocean churning to the west and alerted the lighthouse keepers. On October 5: "...the clouds of clay likely rose about one kilometre in height and solid fragments...reaching an area of 1200 metres around..." The buildings in

1792-409: The erupting vents threw rocks up to a kilometre (0.6 mi) away from the island, and sent ash clouds as high as 10 km (6.2 mi) up into the atmosphere . The loose pile of unconsolidated tephra would quickly have been washed away had the supply of fresh magma dwindled, and large clouds of dust were often seen blowing away from the island during this stage of the eruption. The new island

1856-433: The eruption center were 2.4 °C (4.3 °F) higher than surrounding waters. At 07:15 UTC on 14 November 1963, the cook of Ísleifur II , a trawler sailing these same waters, spotted a rising column of dark smoke southwest of the boat. The captain thought it might have been a boat on fire, and ordered his crew to investigate. Instead, they encountered explosive eruptions giving off black columns of ash, indicating that

1920-425: The eruption of Surtsey by five years and was studied both by Portuguese and foreign scientists. Located at Cabeço Norte, a volcanic vent releases water vapour with temperatures between 180 °C and 200 °C from the volcano complex. The geographer Christophe Neff is carrying field studies on the pioneer vegetation in the Capelinhos area since 1999. In a recently published paper in “Finisterra” he wrote in

1984-403: The eruption was still in progress. Today only a few scientists are permitted to land on Surtsey; the only way anyone else can see it closely is from a small plane. This allows the natural ecological succession for the island to proceed without outside interference. In 2008, UNESCO declared the island a World Heritage Site , in recognition of its great scientific value. In the spring of 1965,

Caldeira Volcano - Misplaced Pages Continue

2048-411: The eruptions ended, with northern fulmar ( Procellaria glacialis ) and black guillemot ( Cepphus grylle ) being the first species to set up home. Twelve species are now regularly found on the island. A gull colony has been present since 1984, although gulls were seen briefly on the shores of the new island weeks after it first appeared. The gull colony has been particularly important in developing

2112-477: The fertilisation of the soil and resulting promotion of plant life provides a viable habitat for herbivorous insects. The first earthworm was found in a soil sample in 1993, probably carried over from Heimaey by a bird. However, the next year no earthworms were found. Slugs were found in 1998, and appeared to be similar to varieties found in the southern Icelandic mainland. Spiders and beetles have also become established. The only significant human impact

2176-466: The first vascular plant was found growing on the northern shore of Surtsey, mosses became visible in 1967, and lichens were first found on the Surtsey lava in 1970. Plant colonisation on Surtsey has been closely studied, the vascular plants in particular as they have been of far greater significance than mosses, lichens and fungi in the development of vegetation. Mosses and lichens now cover much of

2240-545: The first time that a submarine eruption was documented from beginning to end. Its location near an inhabited island with good communications meant it could be intensively studied. The first activities during the eruption were identified by engineer Frederico Machado, the Director of the District Public Works Department, his assistant engineer João do Nascimento and surveyor António Denis, under the authorization of

2304-486: The island (except for Matriz, Conceição and Angustias). The Caldeira Volcano is the main geomorphological unit, corresponding to a polygenetic volcano two kilometers at the top and one kilometer at the base. The walls of the crater rim are abrupt, although their slopes increase with altitudes. The superficial cover of the volcano is covered in pyroclastic material, such as pumice rock, phreatic and phreatomagmatic deposits, evidence of pyroclastic flows and lahars. The flanks of

2368-406: The island include whooper swans ( Cygnus cygnus ), various species of geese , and common ravens ( Corvus corax ). Although Surtsey lies to the west of the main migration routes to Iceland, it has become a more common stopping point as its vegetation has improved. In 2008, the 14th breeding bird species was detected with the discovery of a common raven's nest. According to a 30 May 2009 report,

2432-474: The island is unlikely to be enlarged in the future by further eruptions. The heavy seas around the island have been eroding it ever since the island appeared, and since the end of the eruption almost half of its original area has been lost. The island currently loses about 1.0 hectare (2.5 acres) of its surface area each year. As a suspected part of the Iceland plume , this island is unlikely to disappear entirely in

2496-484: The island than harbour seals , but both are now well established. The presence of seals attracts orcas , which are frequently seen in the waters around the Vestmannaeyjar archipelago and now frequent the waters around Surtsey. On the submarine portion of the island, many marine species are found. Starfish are abundant, as are sea urchins and limpets . The rocks are covered in algae , and seaweed covers much of

2560-424: The island will survive for many centuries. An idea of what it will look like in the future is given by the other small islands in the Vestmannaeyjar archipelago, which formed in the same way as Surtsey several thousand years ago, and have eroded away substantially since they were formed. A classic site for the study of biocolonisation from founder populations , Surtsey was declared a nature reserve in 1965, while

2624-437: The island, but Iceland quickly asserted that the new island belonged to it. By early 1964, the continuing eruptions had built the island to such a size that sea water could no longer easily reach the vents, and the volcanic activity became much less explosive . Instead, lava fountains and flows became the main form of activity. These resulted in a hard cap of extremely erosion-resistant rock being laid down on top of much of

Caldeira Volcano - Misplaced Pages Continue

2688-614: The island. During the island's first 20 years, 20 species of plants were observed at one time or another, but only 10 became established in the nutrient-poor sandy soil. As birds began nesting on the island, soil conditions improved, and more vascular plant species were able to survive. In 1998, the first bush was found on the island, being a species of willow ( Salix ssp.)—a tea-leaved willow ( Salix phylicifolia ), which can grow to heights of up to 4 metres (13 feet). By 2008, 69 species of plant had been found on Surtsey, of which about 30 had become established. This compares to

2752-467: The island. When a large, grass-covered tussock washed ashore in 1974, scientists took half of it for analysis and discovered 663 land invertebrate specimens, mostly mites and springtails , the great majority of which had survived the crossing. The establishment of insect life provided some food for birds, and birds in turn helped many species to become established on the island. The bodies of dead birds provide sustenance for carnivorous insects, while

2816-447: The land by 2.4 km , it spawned 300 seismic events, hurled ash 1 km, destroyed 300 houses in the parishes of Capelo and Praia do Norte and caused the evacuation of 2,000 people (emigration to the US and Canada ). On October 25, the volcano entered a period of dormancy. It is a part of an active fissural volcanic complex which creates multiple seismic and volcanic events. Capelinhos

2880-511: The location of Surtsey. Another station in Reykjavík recorded even weaker tremors for ten hours on 12 November at an undetermined location, when seismic activity ceased until 21 November. That same day, people in the coastal town of Vík 80 km (50 mi) away noticed a smell of hydrogen sulphide . On 13 November, a fishing vessel in search of herring, equipped with sensitive thermometers, noted sea temperatures 3.2 km (2.0 mi) SW of

2944-624: The loose volcanic pile, which prevented the island from being washed away rapidly. Effusive eruptions continued until 1965, by which time the island had a surface area of 2.5 km (0.97 sq mi). On 28 December 1963, submarine activity to the northeast of Surtsey began, causing the formation of a ridge 100 m (330 ft) high on the sea floor. This seamount was named Surtla [ˈsʏr̥tla] , but never reached sea level. Eruptions at Surtla ended on 6 January 1964, and it has since been eroded from its minimum depth of 23 to 47 m (75 to 154 ft) below sea level. In 1965,

3008-415: The meeting of lava and sea water meant that the island consisted of a loose pile of volcanic rock ( scoria ), which was eroded rapidly by North Atlantic storms during the winter. However, eruptions more than kept pace with wave erosion, and by February 1964, the island had a maximum diameter of over 1,300 metres (4,265 feet). The explosive phreatomagmatic eruptions caused by the easy access of water to

3072-467: The near future. The eroded area consisted mostly of loose tephra , easily washed away. Most of the remaining area is capped by hard lava flows, which are much more resistant to erosion. In addition, complex chemical reactions within the loose tephra within the island have gradually formed highly erosion-resistant tuff material, in a process known as palagonitization . On Surtsey, this process has happened quite rapidly, due to high temperatures not far below

3136-478: The ocean waters off the coast of Ponte dos Capelinhos began to boil, and the first vapours were witnessed around 6:30 a.m. one kilometre northwest of the lighthouse. A constant tremor could be sensed, at times reaching a Level IV on the Mercalli scale (MM-31). Three days later, the activity increased; black ash (to about 1400 m) and water vapour (to about 4000 m) rose west of the two ilhéus (English: islets ) off

3200-546: The originally barren island. The undersea vents that produced Surtsey are part of the Vestmannaeyjar submarine volcanic system, part of the fissure of the sea floor called the Mid-Atlantic Ridge . Vestmannaeyjar also produced the famous eruption of Eldfell on the island of Heimaey in 1973. The eruption that created Surtsey also created a few other small islands along this volcanic chain, such as Jólnir and other, unnamed peaks. Most of these eroded away fairly quickly. It

3264-532: The plant life on Surtsey, and the gulls have had much more of an impact on plant colonisation than other breeding species due to their abundance. An expedition in 2004 found the first evidence of nesting Atlantic puffins ( Fratercula arctica ), which are abundant in the rest of the archipelago . As well as providing a home for some species of birds, Surtsey has also been used as a stopping-off point for migrating birds, particularly those en route between Europe and Iceland. Species that have been seen briefly on

SECTION 50

#1732858331211

3328-486: The sea. This intense eruption occurred until the end of October with constant ash raining on Faial, destroying cultural lands, inhibiting normal farming and forcing the residents from local villages to evacuate. By October 10, the eruption had initially formed a small island, baptized Ilha Nova (English: the New Island ), Ilha dos Capelinhos (English: Island of Capelinhos ) or Ilha do Espírito Santo (English: Island of

3392-577: The stratovolcano also include the Morro de Castelo Branco and peninsula of denser material that have resisted erosion. Capelinhos The Capelinhos (from Capelo + -inhos diminutive, which literally means "little cape") is a monogenetic volcano located on the western coast of Faial Island in the Azores . It is part of the larger volcanic complex of Capelo, which includes 20 scoria cones and lava fields that are aligned west-northwest to east-southeast from

3456-489: The submarine slopes of the volcano, with its densest cover between 10 and 20 metres (33 and 66 ft) below sea level. Insects arrived on Surtsey soon after its formation, and were first detected in 1964. The original arrivals were flying insects, carried to the island by winds and their own power. Some were believed to have been blown across from as far away as mainland Europe . Later insect life arrived on floating driftwood , and both live animals and carcasses washed up on

3520-403: The surface. Estimates of how long Surtsey will survive are based on the rate of erosion seen up to the present day. Assuming that the current rate does not change, the island will be mostly at or below sea level by 2100. However, the rate of erosion is likely to slow as the tougher core of the island is exposed: an assessment assuming that the rate of erosion will slow exponentially suggests that

3584-406: The two Ilhéus off the coast of Ponte dos Capelinhos had disappeared under the sand and ash. During this period the cinder cone and isthmus became an integral part of the island of Faial, destroying the roofs of the local buildings and infilling the space to the lighthouse . From May 12–18, 450 seismic events were recorded as the volcano moved into a Strombolian phase, emitting projectiles 500 m into

3648-403: Was 1.3 km (0.50 sq mi). The most recent survey (2007) shows the island's maximum elevation at 155 m (509 ft) above sea level. The new island was named after Surtr , a fire jötunn or giant from Norse mythology . It was intensively studied by volcanologists during its eruption, and afterwards by botanists and other biologists as life forms gradually colonised

3712-514: Was about one cubic kilometre (0.24 cu mi), and the island's highest point was 174 metres (571 feet) above sea level at that time. Since the end of the eruption, erosion has seen the island diminish in size. A large area on the southeast side has been eroded away completely, while a sand spit called Norðurtangi (north point) has grown on the north side of the island. It is estimated that about 0.024 km (0.0058 cu mi) of material has been lost due to erosion—this represents about

3776-540: Was formed. It was named Jólnir , and over the following eight months it appeared and disappeared several times, as wave erosion and volcanic activity alternated in dominance. Activity at Jólnir was much weaker than the activity at the main vent, and even weaker than that seen at Syrtlingur, but the island eventually grew to a maximum size of 70 m (230 ft) in height, covering an area of 0.3 km (0.12 sq mi), during July and early August 1966. Like Syrtlingur, though, after activity ceased on 8 August 1966, it

3840-423: Was initially about 20 cm (8 in) per year but slowed to 1–2 cm (0.39–0.79 in) a year by the 1990s. It had several causes: settling of the loose tephra forming the bulk of the volcano, compaction of sea floor sediments underlying the island, and downward warping of the lithosphere due to the weight of the volcano. Volcanoes in the Vestmannaeyjar archipelago are typically monogenetic , and so

3904-467: Was marked by the predominance of a Hawaiian/Strombolian eruptive process, that was composed of basaltic and benmoreitic rocks. The secondary, Upper group, was a highly explosive period (sub-Plinian in character), which produced a series of twelve deposits of pumice and surge deposits (pyroclastic flows of trachytic and benmoreitic). The volcano was reduced by around 300 m (980 ft) in height due to an eruption that occurred around 1000 years ago. This

SECTION 60

#1732858331211

3968-493: Was named after the fire jötunn Surtur from Norse mythology ( Surts is the genitive case of Surtur , plus -ey , island ) by the Icelandic Naming Committee . Three French journalists representing the magazine Paris Match notably landed there on 6 December 1963, staying for about 15 minutes before violent explosions encouraged them to leave. The journalists jokingly claimed French sovereignty over

4032-409: Was one of the last major explosive events recorded in the Azores. Although the central volcano has not been active within the past two centuries, it has seen activity related to the eruption of Capelinhos (1957–58). During this period, fumaroles in the caldera became active, and the minor lakes/swamps were dried-up by excessive heat. The volcano, due to its central nature, is part of each parish on

4096-403: Was rapidly eroded, and dropped below sea level during October 1966. Effusive eruptions on the main island returned on 19 August 1966, with fresh lava flows giving it further resistance to erosion. The eruption rate diminished steadily, though, and on 5 June 1967, the eruption ended. The volcano has been dormant ever since. The total volume of lava emitted during the three-and-a-half-year eruption

#210789