What is a geyser? What is a volcano geyser? Ice land. Geysers and volcanoes
1. The emergence of volcanoes and their structure. Vulcan - mountain conical shape, from the neck of which flammable gas, steam, ash, stones, etc. are emitted. rocks, and also at the same time powerful streams of hot lava spread across the surface of the earth (Fig. 38). Magma located deep in earth's crust, along the cracks formed, rushes upward and pours out onto the surface. The pouring magma is called lava, and the neck (channel) through which the magma rises is called the vent of a volcano. The vent at the top of the mountain ends in a cup-shaped depression - a crater (in Greek crater - large bowl).
Rice. 38. Structure of the volcano (section): a - crater; b - vent; V - side crater; G- source of magma.
The mouth of the crater is a source of lava-magma. A volcanic eruption is accompanied by an underground roar, and gases and water vapor come out of the crater with a roar. Steam and ash, rising to a great height in the form of a column, form clouds at the top. Ashes in the form tiny particles dust settles around the volcano, covering the surrounding area with a huge thickness. As a rule, clouds gather over the volcano, thunder rumbles, lightning flashes and heavy rain falls.
On mountain slopes, water mixed with ash forms powerful mud flows that rush down, destroying populated areas and devastating everything in its path. Immediately after this, fiery-hot lava bursts out of the crater and spills onto the surface of the earth.
Cities Ancient Rome Pompeii and Herculaneum were destroyed and covered with ash during the eruption of Mount Vesuvius. Only after many years the surface of compacted ash and hardened lava was covered with fertile soil and dense vegetation.
2. Extinct and active volcanoes. How to distinguish an extinct volcano? The cone-shaped shape of the mountain and the crater at the top indicate their active life in the past. Volcanoes whose eruptions have not been recorded in human history are called extinct volcanoes. For example, extinct volcanoes include Elbrus and Kazbek in the Caucasus.
Sometimes extinct volcanoes begin to erupt. For example, in 1960 in Chile, during an earthquake, volcanoes that were considered extinct began to erupt. Therefore, it would be more accurate to call them “asleep.”
Volcanoes that constantly erupt from their vents are called active volcanoes. For example, Klyuchevskaya Sopka in Kamchatka (Fig. 39).
Rice. 39. Volcano Klyuchevskaya Sopka.
The spread of volcanoes on Earth is associated with earthquakes and mountain building.
Active volcanoes are widespread in areas with ongoing mountain building. In such places, magma quickly finds its way to the surface of the earth. Volcanoes are usually located in a chain along cracks in the earth's crust. An individual volcano is rare. Most volcanoes are located on the coast
Pacific Ocean. This place is called the Pacific Volcanic Belt.
Volcanoes erupt not only on land, but also at the bottom of oceans and seas. Near the crater of such a volcano, a new island appears underwater. For example, Kuril Islands in the Pacific Ocean are extinct volcanoes.
These islands have many densely populated areas, cities and industrial centers.
In 1883, a strong eruption of the Krakatoa volcano occurred on one of the small islands in Indonesia between Asia and Australia. Due to the powerful explosion, many parts of the island disappeared. The ash that rose to the upper layers covered the sky for several months. A high wave arose on the sea, which reached the Indian and Pacific Oceans. Several cities and villages of the neighboring island were washed away by a giant wave and tens of thousands of people died.
3. Why are volcanoes studied? The significance of volcanic activity.
Volcanic eruptions provide scientists with information about the composition and properties of substances found in the lithosphere. Studying volcanoes helps determine the origin of minerals. Thanks to research, it is possible to predict the onset of a volcanic eruption and prevent disasters.
Scientists have found that the areas of earthquakes and volcanic eruptions often coincide. These phenomena are typical for areas with unstable earth's crust.
You know that when a volcano erupts, water vapor and gas are released. Many scientists in lately believe that the presence of water on earth's surface And a certain amount oxygen in the atmosphere is associated precisely with volcanic phenomena.
Thus, volcanoes perform important role during the formation of the lithosphere, hydrosphere and atmosphere.
4. Hot springs and geysers. In some areas of the world, the temperature of groundwater is high and various salts and gases are found in dissolved form. Such underground waters are called mineral waters. Mineral water has a certain taste and smell. The appearance of such waters is associated with the presence of a chamber of magma that has not yet cooled down near them. Magma, heating the water, dissolves the salts.
One of the phenomena of volcanic action are geysers (in Icelandic Geiza - gush).
Rice. 40. Geyser.
From time to time, a gushing source of hot water with steam is called a geyser (Fig. 40). Hot water with a temperature above 100°C, flowing from the bowels of the earth, rises through cracks. Hot steam first emerges from the neck of the geyser, followed by hot water bursting out to a height of several tens of meters. All this is accompanied by a strong roar. The geyser gushes for 1-2 minutes and stops until the next accumulation of hot water and steam. Geysers are common in the Pacific volcanic belt - in Kamchatka, Japan, New Zealand, on the coast of North America and on the island of Iceland.
1. How is a volcano formed?
2. Describe the structure of a volcano.
3. Why is it necessary to study volcanoes?
4. What is the role of volcanic activity in the formation of the Earth's surface?
5. Under what conditions do hot springs and geysers appear?
6. On contour map mark areas of frequent earthquakes and volcanoes. Comparing the compiled map with physical card, determine the relationship between the location of seismic and volcanic areas and the relief of the Earth.
7*. Let's say you find yourself in an area where volcanic activity previously occurred. What signs can be used to prove that there is an extinct volcano nearby?
What a geyser is, ordinary people know mainly from school geography. Volcanologists, some tourists and residents of seismically active regions get to see this natural phenomenon live.
Terminology
By definition, a geyser is one of the manifestations of late volcanism, which is expressed in the periodic release of water in a liquid or vapor state into the air. Speaking in simple language, this is a kind of source, gushing out from under the ground at one time or another. Geysers can be mud, water or steam, depending on the temperature and the presence of impurities along the path of their eruption.
Despite the rather banal definition, in fact this natural phenomenon is considered one of the most spectacular and mysterious on the planet. This is eloquently evidenced by the popularity of the most famous geysers, the flow of tourists to them does not dry up, despite a certain danger.
Physics of the process
In order to understand on what principle such a source operates and where so much hot water comes from underground, one should turn to the study of volcanic activity. After all, geysers are mainly formed not on their own, but near a more formidable and dangerous fellow. However, the volcano does not have to be active. The most famous and spectacular geysers are located on the site of extinct or sleeping giants.
From school curriculum Everyone knows that in the depths of our planet there is hot magma. It is also known about her constant attempts to get out, sometimes this succeeds, which is accompanied by earthquakes. This process is very destructive and sometimes ends with a change in the landscape.
A dormant volcano, like an active one, contains hot magma inside itself, but it does not come out, waiting in the wings and accumulating energy. But, as you know, the bowels of the earth are no less rich in water, which, making its way to the surface, becomes springs, streams and even rivers. In order to understand what a volcanic geyser is, you need to imagine the following. Let's say that at a certain distance from the dormant magma one of the water flows. The water in it heats up, expands and tries to find a way out. Ultimately, she gets it in the form of a fountain or cloud of steam. It all depends on the exact temperature to which the heating occurred. It turns out that the volcano itself is sleeping, its energy is not enough to erupt magma, but it is quite enough to push out or even boil water.
Mud geyser
Residents know very well what it is. settlements located near healing plants (and not only) Making its way to the exit, water passes through the layers of the most different breeds, dissolving them. In the case when a fountain shoots directly near a place passing through layers of frozen magma, it often remains more or less transparent. Encountering softer and more pliable rocks along the way, the water mixes with them, and a gurgling mud mass comes to the surface.
Quite often it contains microelements useful for humans, which, thanks to the comfortable temperature, form a thermal source, ideal for treatment. Europe (in particular, Bulgaria) is rich in resorts built on the site of such geysers. North America, Australia and New Zealand. Has great potential Eastern Siberia, where this industry is not yet very developed, but there are all the necessary prerequisites for this.
Is a geyser dangerous?
Despite all its beauty and mystery, this natural phenomenon is shining example unsurpassed power and energy hidden in the bowels of the earth. Sometimes a geyser is just a warm lake with water periodically splashing onto the surface and looking quite peaceful and safe. Sometimes it is a multi-meter fountain, bursting out with all the force and suddenness. And it happens that a cloud of steam whistles out from under the ground, creating the impression that the planet is “breathing.”
Therefore, in order to know how safe it is to be near such a source, you need to understand what a geyser is in a particular case. And being in the valley extinct volcano on excursions, be sure to listen to the guide’s recommendations. After all main danger Most geysers are hidden in their suddenness. As a rule, tourists are not allowed close to powerful and too hot fountains.
The most famous geysers on the planet
They are located mainly in zones of volcanic activity. If we consider the most remarkable in terms of entertainment and scale, then first of all we should pay attention to Yellowstone national park in the USA. It is a huge area where about 500 geysers are concentrated, which makes up 60% of all thermal springs on the planet. The largest of them is called Steamboat and reaches 120 meters.
Slightly smaller in size, but no less spectacular, the Valley of Geysers is located in Kamchatka. There are about 200 different sources here. Looking at such greatness of nature, one can to the fullest understand what a geyser is. The definition cannot convey this in words. The beautiful and at the same time majestic play of water, steam and minerals is sometimes breathtaking.
Geyser Park in Iceland ranks third both in size and number of sources. Maximum height The fountains here reach 60 meters. This is undoubtedly stunning, but the height of the geysers is half that of Yellowstone Steamboat.
You can see what a geyser is by visiting the states of Nevada and Alaska, where there are also quite a few of them. The North Island of New Zealand and Chile are famous for them.
The most mysterious geyser
This status was deservedly received by the American Fly, located in Thanks to the rich mineral composition, his surroundings received a unique coloring. The fly is a collection of several fountains erupting from hills formed by minerals, reaching 1.5 meters and continuing to grow.
It is noteworthy that the geyser was created by man (albeit by accident). Drillers stumbled upon an underground thermal spring at the beginning of the last century while trying to build a conventional well. Currently, Fly is closed to tourists, but due to its height, the geyser is clearly visible from the road.
To understand what a geyser is, theoretical knowledge is not enough. To represent all the beauty and power of this natural phenomenon you need to travel to see it with your own eyes.
The state of Iceland is located on the island of the same name in the Atlantic Ocean, not far from the Scandinavian Peninsula. Total area is 103,000 square km, the length of the coastline is 6,000 km. Northern and east coast The country is represented by fjords and bays, cutting deeply into the high shores. The southern and western sides are dominated by lowlands, close to which lagoons and large bays approach.
Relief of Iceland
The relief of Iceland is a plateau with steep cliffs. Its height reaches 400 - 600 m. On the Icelandic plateau there are volcanic mountains and high-mountain plateaus. The height of individual peaks reaches 2,000 m.
The lowlands of Iceland occupy the southern, western and southwestern parts of the island. In relation to the plateau, they make up 7% of the state's territory. The lowlands are mostly swampy.
Geologically, the island of Iceland is a young formation. Its relief is clear evidence of volcanic origin. Almost all types of volcanoes on the globe are represented on the island. Craters that appear along tectonic faults and cracks are often encountered.
Eruptions and earthquakes occur regularly on the island. Active volcanic activity in Iceland is the reason for the appearance of many thermal springs and geysers in the country.
Volcanoes of Iceland
The largest volcano in Iceland. Active. Its height is 2,119 m. It is the largest glacier in the country.
The peaks of Éraiväjökull are covered with ice. In total, two eruptions have been recorded in the history of the island: an explosive one with floods, in 1362, and a protracted one, in the period from 1727 to 1728.
The volcano, which is the symbol of Iceland. Active. It erupts regularly once every 50 years. Its height is 1,491 m. Its last eruption occurred in 2000.
This is a conical stratovolcano, the top of which is almost always hidden by a cloud cap. Previously, trees and other vegetation grew on the slopes of its mountains; today there are no plants.
Another stratovolcano in Iceland, 1,516 m high. Located in the center of the Icelandic plateau, it is active. The last eruption took place in 1961.
In the caldera of the Askja volcano there are two lakes that were formed as a result of the 1875 eruption:
- Lake Eskvatn is the deepest lake in the country, 220 m deep, today covered with ice;
- Lake Viti is geothermal with milky blue water that emits a sulfur smell.
The presence of lakes has made the volcano a tourist attraction.
A shield-type volcano, represented by hundreds of craters. Its length is 25 km, the highest point is 818 m.
The volcano is active. One of its eruptions, which took place in 1783-1784, became the most destructive in the last millennium. The length of the erupted lava flow was 130 km. About half of the country's total livestock was destroyed. The triggered melting of glaciers led to floods that killed 20% of the population.
Weather disasters have affected the entire Northern Hemisphere of the earth. The air temperature dropped by several degrees throughout the year.
The second highest volcano in Iceland, 2,009 m. It is a subglacial stratovolcano. Active. The extreme period of his activity began in 2007, since then the intensity of activity began to increase. Eruptions are accompanied by tremors.
The last eruption occurred in August 2014. The magnitude of the fluctuations reached 5 points, hot lava came out of the faults to the surface. Residents of the surrounding area were evacuated.
Geysers of Iceland
It is a major tourist attraction. Located in the Høykadalur valley. During rare periods of activity, it throws a column of water onto the ground, reaching a height of 60 m. During the period of hibernation, it turns into a shallow lake with green water. The inactive state may persist for several years.
The activity of the geyser depends on seismic processes and volcanic activity. An active state with eruptions up to 8 times a day was observed in 2000. In the 80s of the last century, artificial influence on the activity of the geyser by adding soap was actively practiced. Due to environmental problems this practice was abolished, and such enforcement measures are now applied exclusively on the country's independence day, June 17.
The geyser is located near the Great Geyser. Is active. The height of the column of water can reach 30 m. The periods between eruptions are 5 - 6 minutes, and it is not uncommon for a geyser to erupt up to 3 times in a row.
The geyser is surrounded by small lakes with blue and clear water, which are hot underground waters that have come to the surface. The area where the geyser is located also smells of hydrogen sulfide.
Volcano Etna(island of Sicily, Italy), under the slope of which one of the largest cities in Sicily, Catania, is comfortably located, not only the largest and high volcano in Europe, but also one of the most active on the planet. Eruptions occur both at its peak and on its slopes.
Volcanic activity on Mount Etna's summit can last for years or even decades without stopping (for example, from 1955 to 1971 or from 1995 to 2001). And eruptions on a mountainside can last from a few hours to more than a year. In 1991-1993 it lasted 472 days.
Just a hundred years ago there was only one crater on the top of Etna - the Central one. But now there are four of them. These are Voragine (Italian: “abyss”) and Bocca Nuova (Italian: “new mouth”), formed respectively in 1945 and 1968 inside the Central Crater. Two more - this is the Northeast crater - highest point mountains, 3330 m, appeared in 1911, as well as the youngest and, as is typical for young people, the most active - the Southeast crater, “born” in 1971.
Volcanologists distinguish several types of eruptions. For example, the volcanic type, named after Fr. Vulcanos are short, strong, but relatively small explosions that release viscous magma and eject material into the air that can reach speeds of up to 350 meters per second. With the Strombolian type (from the island of Stromboli), the volcano erupts continuously over several months or years, throwing out large number liquid lava, bombs and pieces of hot slag. If an eruption is characterized by a large volume of very liquid lava coming out of fissures, then it is a Hawaiian type of eruption. And the most powerful eruptions are of the Plinian type: powerful and sudden explosions with the release of viscous lava and a column of gas and dust, the height of which can reach 50 km.
Etna combined several types. Eruptions of this volcano can be accompanied by explosions, lava flows, the release of gas, ash, pieces of slag and other material.
Etna is a stratovolcano. These are cone-shaped mountains that can be imagined as a layer cake: instead of dough there is a layer of frozen lava, instead of cream there are ash and debris that are formed during the next eruption. This is how the volcano grows, layer by layer. The vent at the bottom is connected to the magma chamber, and at the top is crowned with a crater.
Fumaroles- This is the release of hot volcanic gas and steam. They are different, for example in composition: sulphurous - solfatars or carbonic - mofets. And they are not only visible, but sometimes also heard. The gas escaping through the holes may hiss, whistle, or even burst out of the ground with a roar. This little fumarole in the photo above didn’t even hiss, but snored barely audibly.
Volcanic gas consists of 50-85% water vapor. Over 10% falls on the share carbon dioxide, about 5% is sulfur dioxide, 2-5% is hydrogen chloride and 0.02-0.05% is hydrogen fluoride. Hydrogen sulfide and sulfur gas are usually found in small quantities. Sometimes hydrogen, methane and carbon monoxide are present, as well as small amounts of various metals.
Most often, the proximity of fumaroles can be judged by their smell - strong odor rotten eggs, that is, hydrogen sulfide, which is part of the gas. Deposited on the surface, sulfur gives the surrounding soil a bright yellow.
In 122 BC. Etna erupted explosively, during which falling ash and lapilli - tiny pieces of porous lava - broke the roofs of many buildings in the city of Catania. But its population was exempt from paying taxes for 10 years!
Etna is located at the junction of African and Eurasian tectonic plates. Moreover, the first one moves towards the Eurasian one, plunging under it. The eruptions of Etna are associated precisely with the fact that the downward plate melts and raises the Eurasian plate.
Etna consists of an ancient shield volcano, on top of which a young stratovolcano “grew”. Eruptions of the shield volcano began about 500 thousand years ago, and the stratovolcano began to form about 35 thousand years ago from viscous trachyte lava.
During volcanic eruptions, gas, ash and different materials- from miniature lapilli to volcanic bombs, stuck together lumps of lava. And mixing lava with sand and ash can create porous volcanic tuff. Its color can be any: black, brown, brown, red, orange, yellow, pink or even purple and bluish-white.
Ash clouds from Etna's eruption are especially dangerous for aircraft. If ash particles enter the engine, they can melt and coat moving parts in a layer of glass, which can cause engine failure. Such clouds are often visible from space and repair serious problems for airlines flying to Catania, which is located just a couple of tens of kilometers from the volcano.
Volcanic soils, or Andosols, are formed due to volcanic eruptions and are quite fertile: they are rich in nitrogen, phosphorus and sulfur. At the same time, the volcanic glass contained in them is easily weathered.
Greek island Milos, on which in early XIX century, a statue of Venus was found (and, in fact, that’s why it was called Milo), located on the South Aegean volcanic arc. The island was formed by the eruption of several volcanoes and has an active stratovolcano and many fumaroles. On and near Milos there are geothermal springs whose temperature reaches 300 degrees.
Thermal waters- These are underground waters whose temperature is 20 °C or more. They are often found in areas of active volcanism. The depth of thermal groundwater depends on climate zone: in areas of permafrost development it is 1500-2000 m, in the subtropics - up to 100 m, and in the tropics these waters often come to the surface.
« Tatopani“This is translated from Nepali as “warm water.” In poor mountain villages, such springs significantly make life easier for people: it’s easier to wash dishes, wash clothes, and wash yourself.
Crater Lake Kerid is located in the south of Iceland in the western volcanic zone. The crater is about 3 thousand years old, and by volcanic standards it is quite young, which is why it has managed to maintain an almost ideal shape.
There is no single version about the origin of Kerid. According to one of them, Kerid was once a cinder cone - a small conical volcano, but it exhausted its entire volcanic chamber and sank under its own weight into the resulting cavity.
Iceland is crossed from south to north by the Mid-Atlantic Ridge. This is the boundary between the divergence of the North American and Eurasian tectonic plates in the North Atlantic and the African and South American plates in the South. This partly explains the high volcanic activity on the island. There are more than a hundred “Fire Mountains” in Iceland. These are crater rows, shield volcanoes, stratovolcanoes, mud volcanoes, underwater volcanoes and more.
Geysers (ex. geysa- “break through”, “gushing out”) are hot springs found where there is volcanic activity. The inhabitants of the island are lucky: there are many geysers in Iceland, but they are quite rare in the world. This is mainly due to natural reasons, because geysers almost “live on a volcano”: earthquakes often occur in these places, mudflows and avalanches occur, as a result of which the geysers fall asleep or they lose their power source. This happens quite often in Kamchatka in the legendary Valley of Geysers. There was a landslide there in 2007, and a mudflow occurred in 2014. Both events greatly changed the operation of many geysers.
Valley Høykadalur in the south of Iceland there is a real geyser Klondike. Geyser Strokkur It erupts every five to ten minutes, but the column of water and steam does not rise above 20 meters. And a few tens of meters from it is Geysir, whose name, in fact, became a household name.
Geysir has been active for about 10 thousand years, although during this time it has had its ups and downs. In 1845, it erupted 170 meters, and just a year later - only 54. In late XIX century Geysir gained strength and released a column of water and steam 60 meters several times a day, and in 1916 he almost fell asleep. About 20 years later, a channel was dug around it through a layer of quartz, thanks to which the groundwater level dropped and the geyser became more active. As soon as the channel became clogged with quartz, the eruptions stopped. In the 1990s, the geyser was artificially stimulated to erupt using soap (I’ll tell you how this is done later). But this had a bad effect on the environment, so this method was quickly stopped being used. But after the earthquake in 2000, Geysir “came to life” again and for two days in a row spewed out a column of water and steam to a height of up to 122 meters. IN last time he woke up in February 2016, and is now considered almost asleep.
A geyser erupts because water in underground voids is heated by volcanic heat, turns into steam, and steam pressure pushes the water to the top. However, it turns out that a geyser can be made to erupt even when it was not intended to. Just add (lots of) soap.
Surfactants (which include soaps and detergents) have surface-active properties, meaning they reduce surface tension. Water molecules disperse more easily, and the liquid turns into steam, which rushes upward and carries the water with it.
This method of artificially making a geyser work was discovered in New Zealand in 1901 by pure accident. At this time, on the North Island, in the town of Wai-O-Tapu, an “open prison” was set up - a kind of settlement for criminals who were considered harmless to society. But above all else, Wai O Tapu is an area of high geothermal activity. The prisoners who settled there managed the house and, of course, began to wash their clothes right in these hot springs. One day, after doing laundry, one of them poured a fairly concentrated solution of soap, it seeped through cracks in the rock and triggered a reaction in an underground reservoir, from which water burst out.
By the way, the Lady Knox geyser in Wai-O-Tapu is still launched in this way, but the soap has been replaced by detergents, which are considered less harmful to environment.
Iceland's most famous and infamous volcano, Hekla, refers to fairly active volcanoes. It is about 6-7 thousand years old, and since the beginning of the second millennium AD, about 20 large eruptions and the same number of small ones have occurred. The first written evidence of the Hekla eruption dates back to 1104. In general, from the 13th to the 20th centuries, Hekla was very active and erupted once or twice per century. In 1300, the eruption lasted for a whole year. But since the end of the last century, the volcano has become calmer.
Several mud pots can be seen in the geothermal field Hverir in Iceland. Sulfur colors the field in various shades of yellow and orange, but you want to shut your nose - the corresponding aroma hovers over the field.
Mud Cauldron, as a rule, filled with thick, bubbling clay. Pouring over the edges of the cauldron and cooling, the clay can gradually form walls, resulting in a small mud volcano. However, it has little in common with a real mud volcano.
Hverir belongs to the Krabla volcanic system. Everything on the field is smoking and gurgling. It seems that steam is coming from every crack. Some of them are made by man: in the 50s, several holes were drilled here to study sulfur - this is how “artificial” fumaroles turned out.
A mud boiler is essentially a double boiler. Surface water collected in a shallow tank, the tightness of which is ensured by a layer of clay. Thermal waters heat it from below, and the dirt in the cauldron begins to bubble.
Mud pots are sometimes compared to a paint palette because of the variety of colors surrounding them. For example, iron oxide colors reddish, pink, and beige.
Mud volcanoes They erupt with mud mixed with gas and, usually, water, and sometimes oil.
They, like mud pots, can be found in Russia. A few kilometers from the village of Vulkanovka in Crimea, a pair of mud volcanoes and two mud cauldrons are active. The height of the volcano in the photo above is no more than four meters.
The largest mud volcano in Crimea is considered Jau-Tepe, whose height reaches 60 meters. He was active at the beginning of the 20th century, but last decades sleeping
Thermal springs can create such an unusual lake. Jets of water lift blue silt from the bottom, giving the reservoir an unusual color.
This harsh and inhospitable island (Iceland in translation means “land of ice”) is interesting because the volcanic phenomena here are distinguished by peculiar features that are not repeated anywhere else.
Here, it’s as if the most turbulent, most ancient periods are being reconstructed before us with our own eyes.
Volcanic activity in Iceland
According to the busy volcanic activity Iceland- the most remarkable region of the globe. The manifestation of volcanism, which occurred here on a grand scale in the Tertiary period, has not calmed down to this day.
Lava flows from ancient eruptions stretch like a continuous rocky desert, sometimes for tens of kilometers. The largest of them, Odadahraun (in the northeastern half of the island), is over 130 kilometers long and 30 kilometers wide.
Lava flow The total area under lava flows reaches 7000 square kilometers, i.e. almost equal to Lake Onega (without the northern bays).
There are 26 large ones in Iceland active volcanoes and many small ones. The most famous Hekla volcano(1447 meters in height), crowned with three peaks. The combination of black basalt rocks, black ash and white spots of snow gives Hekla a very gloomy appearance.
This is one of the most active volcanoes: since the 12th century, Hekla has had over 70 eruptions. One of the largest eruptions of Hekla was in 1947.
It lasted for more than a year. The roar of the volcano could be heard 400 kilometers away. The last eruption was in 2000.
From large and small craters, Hekla, in addition to lava, throws out a mass of the finest ash, which plunges a significant part of the island into darkness and covers its vast areas. The ashes are carried far by the wind.
In 1947 it was discovered in southern England, Scandinavia and Finland. The consequences of this eruption caused many disasters to the population, turning the flowering areas closest to the volcano into desert. Not only crops and pastures were severely damaged, but also sheep, who lost their pasture.
Features of lava from Iceland volcanoes
It is interesting to note that the outpouring lava happens in Iceland not only through volcanoes, but also directly from huge cracks. They stretch for tens of kilometers, breaking apart the hills they encounter along the way. The crack faults go 150-200 meters deep. There are especially many of them in the northeastern part of the island. During an eruption, low cones (up to 50 meters) appear above the fissures.
A powerful eruption of lava from the Scaptar fissure, 24 kilometers long, occurred in 1783. Over 90 volcanic craters and cones were formed on it (34 of them up to 50 meters high). The erupted lava covered 900 square kilometers. The average power of the flow reached 30 meters. Total quantity the ejected volcanic products were determined to be approximately 27 cubic kilometers.
The consequence of this eruption was the destruction of livestock feed. Ultimately, earthquakes, famine and epidemics killed 9 thousand people, i.e. almost one fifth of the island's population. In addition, as a result of the eruption, ash completely destroyed crops in Scotland (approximately 1000 kilometers from the eruption area). In Scotland there was also a famine and many people died.
Particularly destructive disasters occur during the eruption of Icelandic volcanoes located among glaciers (more details:) since the outpouring of lava causes massive melting of ice with the formation of mud flows, causing terrible devastation.
Geysers of Iceland
In addition to volcanoes, Iceland is famous for its wonderful geysers. These are peculiar steam-water volcanoes. They periodically emit fountains of hot water and steam (heis in German - hot).
Hot deep waters contain significant amounts of dissolved silica. When water cools, silica precipitates as a white precipitate - geyserite. Over time, a low flat cone with a cup-shaped depression grows from it.
At the bottom of this bowl-shaped pool there is the mouth of a canal that goes 20-30 meters deep. Hot water coming from the channel gradually fills the pool. After a while it boils, and instantly a huge column of water and steam flies up 20-40 meters in height. Some of the water is returned to the pool. The geyser calms down and then again, after 10-20 minutes, or even after 20 hours, the same picture repeats.
The periodicity of the geyser’s action is explained by the fact that superheated water collects at the very bottom of the channel, at approximately 126-127°. However, even at this temperature it does not boil, because the water is pressed by the overlying layers, the temperature of which gradually decreases to 70-80°.
Gradually, thanks to the influx of heat from below, the temperature in the water column rises, steam bubbles begin to appear, then the water boils from the surface - the pressure immediately decreases, and the superheated water, turning into a vapor state, instantly erupts. The water thrown out by the fountain cools, partially returns to the pool and goes into the canal. The influx of superheated deep waters gives birth to a new explosion.
Geysers of other countries
In addition to Iceland, there are geysers in New Zealand, in the USA (in Yellowstone national park), as well as in other countries where volcanic activity occurs or where it occurred before, because how lava retains heat for a long time.
Geysers are known with unrelenting activity for many centuries, but at the same time, the opposite phenomena are also observed, when the geyser gradually fades, turning into a hot spring, or even disappears completely.
On the northern island of New Zealand, even before 1904, the famous, now silent Waimangu geyser operated, throwing out the most powerful fountain in the world, 450 meters high.
Kamchatka is also rich in geysers, especially in the area of the fading Kikhpinych volcano (south of Lake Kronotsky). The bulk of geysers (at least 22 large and about 100 small) are located in the valley of the Geysernaya River.
The most powerful geyser - the Giant - throws out a fountain of water and steam almost 40 meters every 2 hours 50 minutes. The Velkan pool is 3 by 1.5 meters with a depth of at least 3 meters. The water temperature of Kamchatka geysers is 94-99°.
Kamchatka is also rich in hot (from 50-100°) and warm (from 20 to 50°) mineral springs different chemical composition.
In the area of active and especially dying volcanoes, there are mud volcanoes. These are low hills with a depression at the top. Kamchatka mud volcanoes are quite miniature in size - 30 centimeters in height with a crater diameter of 15-10 centimeters.
At times they pour out streams of mud and emit gases. Mud volcanoes are hot and cold. The former are associated with volcanic areas, and the latter - more with oil fields (for example, the Baku fields, the island of Java, Mexico, etc.).
