A volcano is any place where gas, ash, or melted rock come out of the ground. Volcanoes usually all differ in sizes, color, temperatures, and whether they are dormant or not. Once a volcano has been dormant for more than 10,000 years, it is termed extinct, but sometimes volcanoes may make an unexpected return after these years.
Underneath the surface, when the rock in the mantle reaches extremely high temperatures, it melts ( magma) , and builds up alongs with other gases and rocks. The magma then rises up the volcano, until it reaches the volcanic vent, where it erupts. Once magma reaches the surface of the volcano, it becomes lava where it flows down the volcano.
Volcanoes usually occur near or in the middle of major tectonic plate boundaries
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The main and known types of volcanic eruptions are explosive and effusive. Explosive eruptions are when magma rises to the surface, and gets torn into pieces called pyroclasts. Effusive eruptions, however, is when magma rises to the surface where it flows out as lava. There are different styles of these eruptions which include Hawaiian, Strombolian, Vulcanian, Plinian and some other types. Hawaiian eruptions happen when lava is thrown and jetted in the air. A Strombolian eruption is when glowing lava bursts out of the vent of a volcano. Vulcanian eruptions are short, explosions of lava that creates long columns of ash and gas in the air. A Plinian eruption is the most violent and destructive out of all the styles of eruptions. In only a few minutes, long columns of ash, rock,, and gases that rise up to 35 miles high.
Types Of Volcanic Landforms
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Shield Volcanoes
Shield volcanoes have gently sloping sides. These volcanoes usually form when layers of lava erupted from the volcanic vent, and slowly hardens which forms its cone shape.
Cinder Cones
Ash, and lava pieces get erupted in the air, fall down, and harden to make a small vent. These pieces ( called cinder), build up and create a cone shaped volcano called cinder cones.
Composite Volcanoes
A composite volcano, also called a stratovolcano, are cones with layers made up of hardened lava, ash, and other materials. These volcanoes usually develop
Mount Tambora, located on the Island of Sumbawa, Indonesia is classified as a Stratovolcano. Also known as a composite volcano, Tambora is a tall conical volcano (cone like structure) where layers of the walls are built by hardened lava and volcanic ash. The term composite is used to describe the volcano due to the composite layered structure built from sequential outpourings of eruptive materials1. Among the most common types of volcanoes, Tambora also shares its destructive prowess with best-known volcanoes such as Krakota (1883) and Vesuvius (79 A.D). The Island of Sumbawa is located in the middle of the Lesser Sunda Islands chain (a group of islands in the southern Maritime Southeast Asia) and is in the province of West Nusa Tenggara3. A map of Mount Tambora is shown in Figure 1 to provide a better perspective of its location. Interestingly enough, Tambora forms its own peninsula on Sumbawa, known as the Sanggar Peninsula. In April of 1815, after years of dormancy, Mount Tambora erupted with great intensity, approximately 7 on the volcanic explosivity index, which is shown in Figure 2. It has been estimated that the eject volume of Tambora was 160 cubic kilometres, which represents the largest volcanic eruption in recorded history. The death toll has been projected to be at least 71,000 people, of who over 15% were killed directly from the eruption1. The remaining 75% have been thought to succumb to starvation and disease, as the eruptive fallout decimated the agricultural industry in the region. Following the eruption, a volcanic winter ensued. As sun become less abundant due to clouds of ash, crops and livestock perished. Please note that all definitions appearing in the footnotes are either taken from already referenced so...
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
Like most of the other volcanoes in the Cascade Range, St. Helens is a great cone of rubble, consisting of lava rock interlayered with ash, pumice and other deposits. Volcanic cones of this internal structure are called composite cones or stratovolcanoes. Mount St. Helens includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit; another formed Goat Rocks dome on the northern flank. These were destroyed in St. Helens' 1980 eruption.
As Kohala Volcano emerged from the sea and joined with Mahukona, a much larger Big Island began forming. With continued movement of the Pacific Plate, the center of volcanism migrated on to Mauna Kea and Hualalai, the middle-aged volcanoes, and finally on to Mauna Loa and Kilauea, which are the youngest volcanoes on the island. Over the geologically short time of several hundred thousand years, these volcanoes erupted thousands of thin flows which spread over, and built upon, older flows; each volcano growing until it finally emerged from the sea. As time went on, lava flows from one volcano began to overlap flows from other, nearby volcanoes and eventually the peaks coalesced into a single island, the Big Island. In geologically recent times, a new volcano, Loihi, began forming about 18 miles off the southeast coast of the Big Island.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
Super volcanoes are formed when magma rises from the mantle to create a scorching reservoir in the Earth's
Magma is a hot liquid made of melted minerals. Minerals can form crystals when they are cool. Igneous rock can form underground, where the magma cools. slowly. Or, igneous rock can form above ground, where the magma cools.
Volcanoes are one of natures most interesting and dangerous phenomenons. The way volcanoes operate can be understood, on a basic level, by just some simple physics and chemistry, this paper will investigate and explain some of the basic physics that govern the behavior of volcanoes.
Convection currents deep in the mantle of the earth, begin to well up towards the surface. As the pressure increases, it sets the crustal plates in motion. There are different kinds of mountains - Volcanic, Folded, Fault-block, and Dome mountains. Volcanic mountains are formed when magma comes up through cracks in the Earth’s crust and explodes out of lava and ash. The Hawaiian volcanoes, Mt. Hood, Mt. Etna, Vesuvius, and Mt. Saint Helens is an example of volcanic mountains.
There are four major types of study that make up a volcanologist or team of volcanologists. These include physical volcanologists, geophysicists, geodesic volcanologists and geochemists (What does a volcanologist do?, n.d.). Physical volcanologists study the actual processes that make up a volcanic eruption. They also study the deposits made during the eruption. Where the rocks from the eruption were distributed and what their makeup is.
Volcanoes can cause damage by spewing lava, but earthquakes before the eruption can also cause damage. These earthquakes open fissures and let magma out to the surface. When the magma exits these fissures, streams of lava up to hundreds of feet can shoot into the air. The picture below shows the lava erupting from the fissures created by the earthquakes in...
Igneous rocks are formed from the ejection of earth’s volcanoes. Deep down inside earth’s mantle there lies hot magma. Magma is molten rock that is kept below the surface. This mixture is usually made up of four parts: a hot liquid substance which is called the melt; minerals that have been crystallized by the melt; solid rocks that have made themselves tangled in the melt because of loose materials, and finally gases that have become liquid. Magma is created by an increase in temperatures, pressure change, and a alter in composition. When this magma is ejected from earth’s crust it earns a new name called lava. The lava hardens and becomes an Igneous rock.
Volcanoes are formed when magma is expelled from the Earth’s surface, resulting in volcanic eruptions consisting of ash and lava. Over time, the lava cools and forms into rock on the Earth’s surface. Whenever an eruption occurs, the newly-formed rock from the lava layers continuously until the volcano takes its shape. Volcanic eruptions have taken place for thousands of years, and even today, according to the U.S Geological Survey (2010), there are approximately 1500 active volcanoes located throughout the world.
The interior structure of the earth is made up of crust, the mantle and core (inner core and outer core). Earthquakes occur on the crust. Crust forms the external layer of the earth surface. On the crust, the plate tectonics forces are in charge of causing the abrupt earth movements. Due to the existence of an immense temperature and concurrent pressure difference in the outer layer and inner layer of the earth, convection currents occur at the mantle. This energy results from overwhelming decomposition of radioactive substances contained by the rocks found at the interior of the earth. The developed convection currents lead to movement of lava; cold lava finds its way to the interior of the earth crust, while the molten lava which is generally hot, leaves the interior of the earth to the outside of the earth crust. These kinds of circulations occur at different locations of the earth surface and consequently results in segmentation of the earth due to movement in different directions.