Integrated Authority File
The Integrated Authority File or GND is an international authority file for the organisation of personal names, subject headings and corporate bodies from catalogues. It is used for documentation in libraries and also by archives and museums; the GND is managed by the German National Library in cooperation with various regional library networks in German-speaking Europe and other partners. The GND falls under the Creative Commons Zero licence; the GND specification provides a hierarchy of high-level entities and sub-classes, useful in library classification, an approach to unambiguous identification of single elements. It comprises an ontology intended for knowledge representation in the semantic web, available in the RDF format; the Integrated Authority File became operational in April 2012 and integrates the content of the following authority files, which have since been discontinued: Name Authority File Corporate Bodies Authority File Subject Headings Authority File Uniform Title File of the Deutsches Musikarchiv At the time of its introduction on 5 April 2012, the GND held 9,493,860 files, including 2,650,000 personalised names.
There are seven main types of GND entities: LIBRIS Virtual International Authority File Information pages about the GND from the German National Library Search via OGND Bereitstellung des ersten GND-Grundbestandes DNB, 19 April 2012 From Authority Control to Linked Authority Data Presentation given by Reinhold Heuvelmann to the ALA MARC Formats Interest Group, June 2012
Hekla, or Hecla, is a stratovolcano in the south of Iceland with a height of 1,491 m. Hekla is one of Iceland's most active volcanoes. During the Middle Ages, Europeans called the volcano the "Gateway to Hell". Hekla is part of a volcanic ridge, 40 km long; the most active part of this ridge, a fissure about 5.5 km long named Heklugjá, is considered to be within Hekla proper. Hekla looks rather like an overturned boat, with its keel being a series of craters, two of which are the most active; the volcano's frequent large eruptions have covered much of Iceland with tephra, these layers can be used to date eruptions of Iceland's other volcanoes. 10% of the tephra created in Iceland in the last thousand years has come from Hekla, amounting to 5 km3. Cumulatively, the volcano has produced one of the largest volumes of lava of any in the world in the last millennium, around 8 km3. In Icelandic Hekla is the word for a short hooded cloak, which may relate to the frequent cloud cover on the summit. An early Latin source refers to the mountain as Mons Casule.
After the eruption of 1104, stories spread deliberately through Europe by Cistercian monks, told that Hekla was the gateway to Hell. The Cistercian monk Herbert of Clairvaux wrote in his De Miraculis: The renowned fiery cauldron of Sicily, which men call Hell's chimney... that cauldron is affirmed to be like a small furnace compared to this enormous inferno. A poem by the monk Benedeit from circa 1120 about the voyages of Saint Brendan mentions Hekla as the prison of Judas. In the Flatey Book Annal it was recorded that during the 1341 eruption, people saw large and small birds flying in the mountain's fire which were taken to be souls. In the 16th century Caspar Peucer wrote that the Gates of Hell could be found in "the bottomless abyss of Hekla Fell"; the belief that Hekla was the gate to Hell persisted until the 19th century. There is still a legend. Hekla has a morphological type between that of a crater row and stratovolcano sited at a rift-transform junction in the area where the south Iceland seismic zone and eastern volcanic zone meet.
The unusual form of Hekla is found on few volcanoes around the world, notably Callaqui in Chile. Hekla is situated on a long volcanic ridge of which the 5.5 km Heklugjá fissure is considered Hekla proper. This fissure opens along its entire length during major eruptions and is fed by a magma reservoir estimated to have a top 4 km below the surface with centroid 2.5 km lower. The tephra produced by its eruptions is high in fluorine, poisonous to animals. Hekla's basaltic andesite lava has a SiO2 content of over 54%, compared to the 45–50% of other nearby transitional alkaline basalt eruptions, it is the only Icelandic volcano to produce calc-alkaline lavas. Phenocrysts in Hekla's lava can contain plagioclase, titanomagnetite and apatite; when not erupting Hekla is covered with snow and small glaciers. Hekla is located on a diverging plate boundary. Hekla is studied today for parameters such as strain, tilt and other movement and seismic activity. Earthquakes in the volcano's vicinity are below magnitude 2 while it is dormant and magnitude 3 when erupting.
The earliest recorded eruption of Hekla took place in 1104. Since there have been between twenty and thirty considerable eruptions, with the mountain sometimes remaining active for periods of six years with little pause. Eruptions in Hekla are difficult to predict; some are short whereas others can stretch into months and years. But there is a general correlation: the longer Hekla goes dormant, the larger and more catastrophic its opening eruption will be; the most recent eruption was on 26 February 2000. One of the largest Holocene eruptions in Iceland was the Hekla 3 eruption circa 1000 BC, which threw about 7.3 km3 of volcanic rock into the atmosphere, placing its Volcanic Explosivity Index at 5. This would have cooled temperatures in the northern parts of the globe for a few years afterwards. Traces of this eruption have been identified in Scottish peat bogs, in Ireland a study of tree rings dating from this period has shown negligible tree ring growth for a decade. A Unless otherwise stated eruption dates are from Global Volcanism Program, other sources disagree.
Hekla 3, 4, 5 produced huge amounts of rhyolitic ash and tephra, covering 80% of Iceland and providing useful date markers in soil profiles in other parts of Europe such as Orkney and elsewhere. H3 and H4 produced the largest layers of tephra in Iceland since the last Ice Age. During the last 7,000 years, one third of the volcanic ash deposited in Scandinavia, Germany and the United Kingdom originated from Hekla. 1104 Hekla had been dormant for at least 250 years when it erupted explosively in 1104, covering over half of Iceland with 1.2 km3 / 2.5 km3 of rhyodacitic tephra. This was the second largest tephra eruption in the country in historical times with a VEI of 5. Farms upwind of the volcano in Þjórsárdalur valley, Hrunamannaafréttur and Lake Hvítárvatn were abandoned because of the damage; the eruption caused Hekla to become famous throughout Europe. 1158A VEI 4 eruption began on 19 January 1158 producing over 0.2 km3 of tephra. It i
A fissure vent known as a volcanic fissure or eruption fissure, is a linear volcanic vent through which lava erupts without any explosive activity. The vent is a few metres wide and may be many kilometres long. Fissure vents can cause large flood basalts which run first in lava channels and in lava tubes. After some time the eruption may concentrate on one or some of them. Small fissure vents may not be discernible from the air, but the crater rows or the canyons built up by some of them are; the dikes that feed fissures reach the surface from depths of a few kilometers and connect them to deeper magma reservoirs under volcanic centers. Fissures are found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are part of the structure of shield volcanoes. In Iceland, volcanic vents, which can be long fissures open parallel to the rift zones where the Eurasian and the North American Plate lithospheric plates are diverging, a system, part of the Mid-Atlantic Ridge.
Renewed eruptions occur from new parallel fractures offset by a few hundred to thousands of metres from the earlier fissures. This distribution of vents and sometimes voluminous eruptions of fluid basaltic lava builds up a thick lava plateau, rather than a single volcanic edifice, but there are the central volcanoes, composite volcanoes with calderas, which have been formed during thousands of years, eruptions with one or more magma reservoirs underneath controlling their respective fissure system. The Laki fissures, part of the Grímsvötn volcanic system, produced one of the biggest effusive eruptions on earth in historical times, in the form of a flood basalt of 12–14 km3 of lava in 1783. During the Eldgjá eruption A. D. 934-40, another big effusive fissure eruption in the volcanic system of Katla in South Iceland, ~18 km3 of lava were released. In September 2014, a fissure eruption is ongoing on the site of the 18th century lava field Holuhraun; the eruption is part of an eruption series in the Bárðarbunga volcanic system.
The radial fissure vents of Hawaiian volcanoes produce “curtains of fire” as lava fountains erupting along a portion of a fissure. These vents build up low ramparts of basaltic spatter on both sides of the fissure. More isolated lava fountains along the fissure produce crater rows of small spatter and cinder cones; the fragments that form a spatter cone are hot and plastic enough to weld together, while the fragments that form a cinder cone remain separate because of their lower temperature. Media related to Eruption fissures at Wikimedia Commons Detailed list and KML files for Fissure Vents Volcanolive.com Page on Fissure Vents
Geothermal power in Iceland
Due to the geological location of Iceland, the high concentration of volcanoes in the area is an advantage in the generation of geothermal energy, the heating and making of electricity. During winter, pavements near these areas are heated up. Five major geothermal power plants exist in Iceland, which produce 26.2% of the nation's electricity. In addition, geothermal heating meets the heating and hot water requirements of 87% of all buildings in Iceland. Apart from geothermal energy, 73.8% of the nation’s electricity is generated by hydro power, 0.1% from fossil fuels. Hydrogen sulfide from geothermal energy has impacted the health of Icelanders. Consumption of primary geothermal energy in 2004 was 79.7 petajoules 53.4% of the total national consumption of primary energy, 149.1 PJ. The corresponding share for hydro power was 17.2%, petroleum was 26.3%, coal was 3%. Plans are underway to turn Iceland into a 100% fossil-fuel-free nation in the near future. For example, Iceland's abundant geothermal energy has enabled renewable energy initiatives, such as Carbon Recycling International's carbon dioxide to methanol fuel process.
Geothermal energy provides tourist attractions such as the Blue Lagoon. The geothermal water originates 2,000 metres below the surface, where freshwater and seawater combine at extreme temperatures, it is harnessed via drilling holes at a nearby geothermal power plant, Svartsengi, to create electricity and hot water for nearby communities. This Blue Lagoon is powered by geothermal energy; the following are the six largest power stations in Iceland: Hellisheiði Power Station Nesjavellir Geothermal Power Station Reykjanes Power Station Svartsengi Power Station Krafla Power Station Þeistareykir Power Station List of power stations in Iceland Renewable energy in Iceland The Geothermal energy exhibition Iceland Deep Drilling Project Renewable energy by country Iceland Energy Authority Icelandic Energy Portal More information about Svartsengi power-plant More information about Nesjavellir power-plant More information about Krafla power-plant More information about Hellisheidi power-plant Photo Gallery from islandsmyndir.is Photo Geothermal power station Svartsengi Photos of Geothermal power plants at Reykjanes & Svartsengi Tiroler Bi Mannvit Engineering of Iceland RES - School for Renewable Energy Science in Iceland Keilir - Atlantic Center of Excellence Icelandic GeoSurvey
Volcanology of Iceland
The volcano system in Iceland that started activity on August 17, 2014, ended on February 27, 2015, is Bárðarbunga. The volcano in Iceland that erupted in May 2011 is Grímsvötn; the volcanoes of Iceland include a high concentration of active ones due to Iceland's location on the mid-Atlantic Ridge, a divergent tectonic plate boundary, its location over a hot spot. The island has 30 active volcanic systems, of which 13 have erupted since the settlement of Iceland in AD 874. Of these 30 active volcanic systems, the most active/volatile is Grímsvötn. Over the past 500 years, Iceland's volcanoes have erupted a third of the total global lava output; the most fatal volcanic eruption of Iceland's history was the so-called Skaftáreldar in 1783-84. The eruption was in the crater row Lakagígar southwest of Vatnajökull glacier; the craters are a part of a larger volcanic system with the subglacial Grímsvötn as a central volcano. A quarter of the Icelandic nation died because of the eruption. Most died not because of the lava flow or other direct effects of the eruption, but from indirect effects, including changes in climate and illnesses in livestock in the following years caused by the ash and poisonous gases from the eruption.
The 1783 eruption in Lakagígar is thought to have erupted the largest quantity of lava from a single eruption in historic times. The eruption under Eyjafjallajökull in 2010 was notable because the volcanic ash plume disrupted air travel in northern Europe for several weeks. In the past, eruptions of Eyjafjallajökull have been followed by eruption of the larger volcano Katla, but after the 2010 eruption no signs of an imminent eruption of Katla were seen; the eruption in May 2011 at Grímsvötn under the Vatnajökull glacier sent thousands of tonnes of ash into the sky in a few days, raising concerns of a repeat of the travel chaos seen across northern Europe. Though a small eruption, the 2010 eruption of Eyjafjallajökull was notable for causing enormous disruption to air travel across western and northern Europe over a period of six days in April 2010. About 20 countries closed their airspace to commercial jet traffic and it affected 10 million travellers. Bárðarbunga is a stratovolcano and is 2,000 meters above sea level in central Iceland.
This makes it the second highest mountain in Iceland. The eruption series, Iceland's largest eruptions in 230 years that started on August 17, 2014 and lasted for 180 days, under the Bárðarbunga system started with an heavy earthquake swarm followed by clusters of volcanic activity that went on for an extended period; this resulted in multiple lava fountain eruptions in Holuhraun. Lava flow came from a dyke over 40 km long. An ice-filled subsidence bowl over 100 square kilometers in area and up to 65 meters deep formed as well. There was limited ash output from this eruption unlike numerous glacial eruptions which are common in Iceland; the primary concern with this eruption was the large plumes of sulphur dioxide in the atmosphere which adversely affected breathing conditions across Iceland, depending on wind direction. The volcanic cloud was transported toward Western Europe in September 2014; the smooth flowing basaltic lava pāhoehoe is in Iceland called helluhraun. It forms rather flat surfaces.
On the other hand, there is less flowing ʻaʻā, on Iceland called apalhraun. The loose, sharp, spiny surface of an ʻaʻā flow makes hiking difficult and slow. Lists of volcanoes Geography of Iceland List of volcanoes in Iceland Geothermal power in Iceland Surtsey Photos of the Grímsvötn and Eyjafjallajökull eruptions Map: active volcanoes of the world Icelandic Video Archive Volcano Discovery: Iceland
A summit is a point on a surface, higher in elevation than all points adjacent to it. The topographic terms acme, apex and zenith are synonymous; the term top is used only for a mountain peak, located at some distance from the nearest point of higher elevation. For example, a big massive rock next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are considered subsummits of the higher peak, are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may refer to the highest point along a line, trail, or route; the highest summit in the world is Everest with height of 8844.43 m above sea level. The first official ascent was made by Sir Edmund Hillary, they reached the mountain`s peak in 1953. Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective; the UIAA definition of a peak is.
Otherwise, it's a subpeak. In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit. A summit climbing differs from the common mountaineering. Summit expedition requires: 1+ year of training, a good physical shape, a special gear. Although a huge part of climber’s stuff can be left and taken at the base camps or given to porters, there is a long list of personal equipment. In addition to common mountaineers’ gear, Summit climbers need to take Diamox and bottles of oxygen. There are special requirements for crampons, ice axe, rappel device, etc. Geoid Hill – Landform that extends above the surrounding terrain Nadir Summit accordance Peak finder Summit Climbing Gear List
Laki or Lakagígar is a volcanic fissure in the south of Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is properly referred to as Lakagígar. Lakagígar is part of a volcanic system centered on the volcano Grímsvötn and including the volcano Thordarhyrna, it lies between the glaciers of Mýrdalsjökull and Vatnajökull, in an area of fissures that run in a southwest to northeast direction. The system erupted violently over an eight-month period between June 1783 and February 1784 from the Laki fissure and the adjoining volcano Grímsvötn, pouring out an estimated 42 billion tons or 14 km3 of basalt lava and clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that contaminated the soil, leading to the death of over 50% of Iceland's livestock population, the destruction of the vast majority of all crops; this led to a famine which killed 25% of the island's human population. The lava flows destroyed 20 villages; the Laki eruption and its aftermath caused a drop in global temperatures, as 120 million tons of sulfur dioxide was spewed into the Northern Hemisphere.
This may have caused droughts in North Africa and India. On 8 June 1783, a 25 km long fissure with 130 craters opened with phreatomagmatic explosions because of the groundwater interacting with the rising basalt magma. Over a few days the eruptions became less explosive and Hawaiian in character, with high rates of lava effusion; this event is rated as 6 on the Volcanic Explosivity Index, but the eight-month emission of sulfuric aerosols resulted in one of the most important climatic and repercussive events of the last millennium. The eruption known as the Skaftáreldar or Síðueldur was a VEI 6, produced an estimated 14 km3 of basalt lava, the total volume of tephra emitted was 0.91 km3. Lava fountains were estimated to have reached heights of 800 to 1,400 m; the gases were carried by the convective eruption column to altitudes of about 15 km. The eruption continued until 7 February 1784, but most of the lava was ejected in the first five months. Grímsvötn volcano, from which the Laki fissure extends, was erupting at the time, from 1783 until 1785.
The outpouring of gases, including an estimated 8 million tons of hydrogen fluoride and an estimated 120 million tons of sulfur dioxide, gave rise to what has since become known as the "Laki haze" across Europe. The consequences for Iceland, known as the Móðuharðindin or "Mist Hardships", were disastrous. An estimated 20–25% of the population died in the famine and fluoride poisoning after the fissure eruptions ensued. Around 80% of sheep, 50% of cattle and 50% of horses died because of dental fluorosis and skeletal fluorosis from the 8 million tons of hydrogen fluoride that were released; the parish priest and dean of Vestur-Skaftafellssýsla, Jón Steingrímsson, grew famous because of the eldmessa that he delivered on 20 July 1783. The people of the small settlement of Kirkjubæjarklaustur were worshipping while the village was endangered by a lava stream, which ceased to flow not far from town, with the townsfolk still in church; this past week, the two prior to it, more poison fell from the sky than words can describe: ash, volcanic hairs, rain full of sulfur and saltpeter, all of it mixed with sand.
The snouts and feet of livestock grazing or walking on the grass turned bright yellow and raw. All water went light blue in color and gravel slides turned grey. All the earth's plants burned and turned grey, one after another, as the fire increased and neared the settlements. There is evidence that the Laki eruption weakened African and Indian monsoon circulations, leading to between 1 and 3 millimetres less daily precipitation than normal over the Sahel of Africa, resulting in, among other effects, low flow in the River Nile; the resulting famine that afflicted Egypt in 1784 cost it one-sixth of its population. The eruption was found to have affected the southern Arabian Peninsula and India. An estimated 120,000,000 long tons of sulfur dioxide was emitted, about three times the total annual European industrial output in 2006, equivalent to six times the total 1991 Mount Pinatubo eruption; this outpouring of sulfur dioxide during unusual weather conditions caused a thick haze to spread across western Europe, resulting in many thousands of deaths throughout the remainder of 1783 and the winter of 1784.
The summer of 1783 was the hottest on record and a rare high-pressure zone over Iceland caused the winds to blow to the south-east. The poisonous cloud drifted to Bergen in Denmark–Norway spread to Prague in the Kingdom of Bohemia by 17 June, Berlin by 18 June, Paris by 20 June, Le Havre by 22 June, Great Britain by 23 June; the fog was so thick that boats stayed in port, unable to navigate, the sun was described as "blood coloured". Inhaling sulfur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts with the moisture in lungs and produces sulfurous acid; the local death rate in Chartres was up by 5 % during September, with more than 40 dead. In Great Britain, the records show, it has been estimated. The weather became hot, causing severe thunderstorms with large hailstones that were report