Volcanoes of the Earth
|Automatic translation||Updated June 01, 2013|
We can not talk about volcanoes without understanding tectonic plates. Tectonic Plates are a theory that revolutionized the vision of geologists. In this theory, the Earth's surface is cut into large plates. The size and position of these plates change in geological time.
This area is called "Ring of Fire". The line of earthquakes and volcanoes coincide line in different places around the world. These areas of intense geologic activity, earthquakes, volcanic eruption or formation of mountains, mark the boundaries between the plates and define lithospheric 7 large plates and 20 smaller ones.
Image: The distribution of volcanoes along the tectonic zones.
Major tectonic plates
The tectonic plates (initially called continental drift) is the current model of the internal functioning of the Earth. The oceanic plates are located at the Mid Ocean wrinkles. At these places, the oceanic crust is very thin, a few kilometers thick lava happens to clear a permanent move to the surface through large cracks long thousands of kilometers. These cracks, called rift ocean is filled with lava that cools getting closer to the area in contact with water. The lava then crystallize on each wall of the crack, making the new oceanic crust by removing the crust the oldest.
This is done to gauge the speed of a few centimeters per year on average and thus Europe and North America were joined there almost 150 million years, were at a distance of another.
Image: The main tectonic plates, bounded by the lines of earthquakes. The plate of North America, South America, of Eurasia, Africa, the Pacific, Australia and Antarctica, are visible in this image.
Characteristics of a volcano
A volcano definition of volcanism, given by an American geologist: "It's all physical and chemical phenomena that accompany the ascent of magma." is composed of three parts: a reservoir of magma in depth, one or more chimneys volcanic communicate with Inside the Earth, and the volcanic mountain which is a Crater, a crater cone, a dome, a lava flow or a deposit product explosion (slicks sanded, etc...)
There are about 1 500 active volcanoes land which erupted sixty enter every year.
Image: The red volcanoes, effusive eruptions are relatively quiet, emit fluid lava in the form of castings, the volcanoes of "hot spot".
Image: The gray volcanic eruptions explosive issue pasty lava and ash in the form of pyroclastic flows and volcanic plumes
Krakatau - Indonesia
Image: Krakatau Google map
Krakatau in Indonesia is a type of explosive volcano which is located in the Sunda Strait between the islands of Sumatra and Java (not to be confused with the island of Krakatau NE Java). Situated 40 km west of Java on Krakatau exploded in August 1883.
The volcanoes may have important consequences on the evolution of humankind, and according to David Keys, archeology correspondent for the British newspaper The Independent, the massive eruption of Krakatau which took place in February 535, is the cause of separation between the two islands of Java and Sumatra. The volcanic ash cloud the entire Earth for two years and caused a drop in temperatures for several years, which would have destroyed crops and led to famine. The planet was then delivered to epidemics, especially the bubonic plague, as described in the writings of the monk Evagrius Scholasticus, a contemporary of the Emperor Justinian, which weakened in part the human race, moving all political, religious and social in the world. Keys provides a series of hypothetical patterns from this eruption: the emergence of Islam, the foundation of modern Judaism, creating what is now Pakistan, China's reunification, the collapse of Mayan civilization, the final decline of the Roman Empire.
Image: Within the crater is a cone pierced three openings still bubbling. The ashes of the Anak Krakatau, formed in 1941, down its slopes to the sea.
Image: Eruption of Krakatau in 1997.
Bromo Volcano - Java - Indonesia
Image: Bromo Google map
There are about 1 500 000 years a huge Stratovolcano, Mount Tengger, probably high of 4,000 m, collapsed from a massive eruption. The gaping hole opened by the disaster in East Java is today one of the most beautiful landscapes of the planet: the Tengger Caldera. The eruptions that can follow the growth of several cones: the Kursi, the Widodaren the Batok and finally, the most famous, the Bromo in activity. This cone of ash incarnation of the god Brahma is revered and feared by the Tengger, Hindu people living near the volcano for centuries. The volcano, very easy to access, is a dangerous tourist attraction in 2004 during an unexpected explosion table there were 3 dead. The Bromo volcano, like all volcanoes, fertilize the fields around and allows for multiple harvests of rice per year through volcanic ash sprinkling regular campaign, coupled with a hot and humid. The Bromo volcano is a sacred place of worship which take place at certain times of the year, large festival in honor of the gods. Thousands of pilgrims in procession then climb to the summit of the volcano to throw their offerings into the crater. Ngadisari is a tiny mountain village, facing one of the largest volcanic landscapes of the world: the vast Tengger caldera. Its crater 20 km in diameter, is filled with volcanic sand-colored brown and ocher. In the center there are several small separate summits. The Batok, an old cone with steep ravines burned. Beside him li.e. the flanks of the true Bromo. A staircase like a Grapple, climbs up to the volcano. Above, a huge crater 300 meters deep for a kilometer wide open on the bowels of the volcano beyond the floor of the caldera on which the volcanic cone. This mouth out a huge plume of steam that can be diluted in the air and hydrogen sulfide unbreathable. The vertical walls are yellowed by sulfur. Volcanic eruptions of the volcano Bromo:
Image: satellite view of the Bromo volcano (top) and the Bromo volcano, photographed during a trip to Asia (bottom).
Etna - Sicily - Italy
Image: Etna Google map
Etna, also called Mongibello (the Mountain of Mountains), is one of the most active volcanoes in the world.
It is likely that the Bocca Nuova near the Voragine, eventually do more than just a huge central crater. Its four craters lie to 2 900 m and this area is a caldera filled by the succession of successive eruptions.
Image: explosive aspect (top) and effusive (bottom) of the Etna.
Stromboli - Italy
Image: Stromboli Google map
The Stromboli volcano is located in the Aeolian Islands or Lipari Islands, north-west of Sicily, Italy. The Aeolian Islands are the Kingdom of the winds and volcanoes.
On 27 February 2007, after a resurgence of explosive activity on the island two fractures effusives have opened in the slope of the Sciara del Fuoco and two lava flows reached the sea, emitting plumes of water vapor. The Italian Protezione Civile often triggers alerts to the village of Ginostra and nearby islands of Panarea, Lipari and Vulcano. A journey to discover this archipelago north of Sicily, can be an introduction to volcanism or the opportunity to enjoy a warm Mediterranean sun on the beaches of black sand. The Stromboli is accessible from Sicily, from Milazzo, from which many aliscafi. It may embark and disembark in Ginostra. It is also possible to go to Stromboli and the Aeolian islands, from Naples. It will take a night boat to reach the Stromboli. For hikers, the Stromboli volcano is dangerous.
Image: The bronze coast of the island of Stromboli are overcome by the Vancori, we see two lava flows in the Sciara del fuoco.
Image: Stromboli: 750 m to the active crater of 300 m in diameter.
Kilauea - Hawaii
Image: Kilauea Google map
The volcano Kilauea, is the eastern edge of Big Island, the Big Island of Hawaii. It appeared there are 200 000 years on the southern flank of Mauna Loa. The Kilauea volcano is a kind of shield A shield volcano is a type of volcano Effusive. It is usually a large conical volcano at its center with a wide crater filled with washing fluid, called lava lake. A little shield volcano shut down and be replaced by a large hole or an acid lake., (20 000 km3, an area of 1 500 km2. It is the latest emerged volcanoes of Hawaii. It is based on the south-east of imposing its neighbor, Mauna Loa. The Kilauea has its own reservoir magma supply and is a separate entity volcanic Mauna Loa.
The lava falling into the water eventually get very specific forms, called "Pillow lavas, which are lava-shaped cushions round. Halemaumau is a pit crater, which is well known in the Parc National des Volcans in Hawaii. The floor of the Kilauea caldera surrounding the Halemaumau.
Image: The eruption of Kilauea in 1983 was projected basaltic lava on the slopes of Mauna Loa, volcano near the island of Hawaii.
Image: Kilauea, Hawaii: Lava fluid in the foreground and viscous lava flow in the background.
Erta Ale - Ethiopia
Image: Erta Ale Google map
The chain of Erta ale is among the axial channels in Afar, the largest and most characteristic. The Erta Alé is located in the north of the great rift valley in the Danakil Depression. Erta Ale means smoking mountain in Afar. It measures, from north to south, over 95 km long and 42 km wide. It is located along the axis of the northern part of the Danakil Depression, descending to - 120 m below sea level, Ethiopia, near the Red Sea. It includes six buildings volcanic Erta Ale, Gada Ale, Alu-Dala Filla, Boral Ale, Hayli GUB, Alé ring. This desert area with no vegetation is the area of lava. The Afar depression, called Dancalie or Danakil in the north, is an area at the intersection of three boundaries of lithospheric plates, is the meeting place of three rifts, the Ethiopian rift continental rifts and two ocean the Red Sea and Gulf of Aden. The active volcano, Erta Alé is only 613 meters heart of the volcanic chain of Erta Ale. It is a shield volcano, 600 m high slopes very low, supported by a base of 30 km in diameter. His summit with the morphology change depending on volcanic activity, has a caldera collapse (1 600 x 700 m) as that found on the summit of Mauna Loa or Kilauea in Hawaii. Its elliptical caldera is stretched by a north-north-west to south-south-east. Within this caldera crater is called Pit (pit crater), with steep walls, which, depending on the activity, one or more lakes of molten lava. Currently there are two craters pits the crater North and South crater.
Erta Alé is one of the few active volcanoes in a lake of molten lava permanent, the heat from the washer reservoir is in equilibrium with the heat dissipated into the atmosphere.
Image: Lake of lava Erta Ale. It is one of three volcanoes in the world, with the Kilauea and Erebus, to contain a permanent lake of lava.
Lengai - Tanzania
Image: Ol Doinyo Lengai Google map
The Ol Doinyo Lengai is a Stratovolcano, i.e. a volcano whose structure is formed from the accumulation of lava, tephra of and / or pyroclastite, conical in shape because of his pasty lava which is hard sells. It is located in Tanzania, in the great rift valley that runs through eastern Africa from North to South. The Ol Doinyo Lengai ( "Mountain of Gods" in Maasai language) is located in northern Tanzania, 70 km from the Kenyan border and 160 km west of Kilimanjaro. This volcano, 370,000 years old, is one of the largest volcanoes in the region and amounts to 2 878 meters, not far from the famous Serengeti Game Reserve. The Lengai, the only active volcano in this area, is also the only volcano on the planet to make carbonatites rich lavas sodium carbonate, iron and calcium, while other volcanoes spew lava globe mainly siliceous. The temperature carbonatites lavas exceptional and unique Lengai vary between 500 and 540 ° C, which is a low temperature compared to temperatures of basalts which are about 1 000 to 1 100 ° C.
In their emissions, these carbonatites are black like oil drain, then after a few minutes they become chocolate. A day later, these flows cooled deteriorate in contact with the atmosphere and the surface takes a white as snow. Its eruptions are rare, a dozen since the late 19th century. Since the last explosive eruption of 1966, which dug a crater 500 meters by 350 meters to 100 meters deep, the activity has resulted in the continuous outpouring of small lava flows that filled the crater. In 1999, flows have spread beyond the crater to slide down the slopes of Langa. The steep and arduous ascent of the volcano Oldonyo Lengai takes 5 to 7 hours of walking in a remote area in the heart of the Rift Valley in Tanzania.
Image: The Lengai spits carbonatites rich lavas sodium carbonate, iron and calcium and low in silica.
Nyiragongo - Democratic Republic of Congo
Image: Le Nyiragongo Google map
The Stratovolcano or Niragongo Nyiragongo is one of the most active volcanoes and dangerous Africa.
Toba - Indonesia
Image: island of Toba Google map
Toba is located on the island of Sumatra, on the subduction zone between the Indo-Australian Plate and Eurasian. The super volcano on the island of Toba in Indonesia is the subject of a catastrophic theory on human evolution by Stanley Ambrose, a professor at the University of Illinois at Urbana-Champaign. Volcanoes can cause massive climate disasters, causing a sudden cooling of the mean temperature of Earth.
In 1998, Stanley Ambrose, said the eruption of Toba caused a global cooling of the planet for 1800 years.
Image: Nestled in the heart of the rainforest of Sumatra, the caldera of the island of Toba has impressive dimensions. With its 30 km wide and 100 km long, the caldera is one of the largest in the world. The ancient caldera is filled by a lake in the middle of which lies the island of Samosir, embodying the old dome of the volcano.
Katla - Island
Katla is a gigantic volcano in southern Iceland covered by an ice cap. This is one of the most active volcanoes and most destructive of Iceland, it is the origin of several Outburst particularly brutal and devastating.
Volcano acquired its present appearance there ≈ 22,000 years ago and 12,000 years, an eruption causes the partial emptying of the magma chamber three kilometers beneath the surface and creates the caldera at the summit of the volcano. Katla is the source of the great volcanic fissure situated in the north-east, about sixty kilometers from the edge of the current icecap.
Image: Katla is part of the eastern volcanic zone of Iceland which includes other volcanoes like Hekla, Laki and the Vatnafjöll. Fluid lavas of this type of volcano are not explosive, but on Katla, the lava to cross the ice cap that increases the explosiveness of lava and causes Outburst.