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A Brief about Volcanoes:
The volcano is an opening or rupture in the earth’s crust that allows the magma, nothing but hot liquid and semi-liquid rocks, along with volcanic ash and gases, to escape. They are found where tectonic plates come together to crash into each other or separate, but they can also occur in the middle of plates due to volcanic hotspots. Volcanic eruption is when lava and gas are released from a volcano.
The most dangerous type of eruption is called a ‘Glowing Avalanche’, which is formed when freshly erupted magma flows down the sides of a volcano. It can travel quickly, and the temperature reaches 1,200 degrees Fahrenheit. Other hazards include ashfall, lahars, mud or debris flows. Volcanoes often cause population displacement and food shortages.
How do Volcanoes erupt?
Volcanoes openings in Earth’s crust release ashes, gases and steam, and hot liquid rock called lava. Most of the world’s volcanoes are found around the edges of tectonic plates, both on land and in the oceans.
On land, volcanoes are formed by one tectonic plate moving under another plate. A thin or heavy oceanic plate subducts or moves under a thicker continental plate. This happens when the ocean plate sinks into the mantle.
In water, water is trapped inside the rocks in this plate when it gets squeezed out. This causes some of the rocks to melt. The melted rock, or magma, is lighter than the surrounding rock and rises. Magma is collected in magma chambers, but it is still miles below the surface.
In the ocean, volcanoes erupt along the cracks, which are opened in the ocean floor by spreading two plates called a mid-ocean ridge. Magma from Earth’s upper mantle rises to fill these cracks. As the lava cools, it forms a new crust on the edges of the cracks. These mid-ocean ridges are long chains of underwater volcanoes that circle the planet like the seams on a baseball.
What are the effective causes of eruptions?
A lot of factors trigger a volcanic eruption.
Still, there are three predominates, which are- the buoyancy of the magma, the pressure from the evolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
The rock inside the earth melts, the mass remains the same while its volume increases, producing a melt that is less dense than the surrounding rock. Thus, the lighter magma rises toward the surface because of its buoyancy. The magma density between the zone of its generation and the surface is less than that of the surrounding and overlying rocks. The magma reaches the surface and erupts.
In an andesitic magma saturated with water and six kilometres below the surface, about 5 percent of its weight is dissolved in water. This magma moves toward the surface, the solubility of the water in the magma decreases, so the excess water separates from the magma in the form of bubbles. The magma moves closer to the surface, more and more water dissolves from the magma, increasing the gas/magma ratio in the conduit. When the volume of bubbles reaches about 75 per cent, the magma disintegrates into pyroclasts which are partially molten and solid fragments and erupts explosively.
The third process holds the cause where volcanic eruptions act as an injection of new magma into a chamber filled with magma of similar or different compositions. This injection forces out some of the magma in the chamber to move up in the conduit and erupt at the surface.
Volcanologists are well aware of these three causes, but still, they cannot yet predict a volcanic eruption. They have still made significant advances in forecasting volcanic eruptions. This forecasting involves the probable character and time of an eruption in a monitored volcano. The character of an eruption is based on the prehistoric and historic record of the volcano in question and its volcanic products. A violently erupting volcano that has produced ashfall, ash flow and volcanic mudflows is likely to do the same.
How do volcanoes affect people?
Volcanoes affect people in many ways. Some in bad ways, houses, buildings, roads, and fields, can get covered with ash. As long as the ash gets off, houses may not collapse, but people often leave because of the ash and are not around to continually clean off their roofs. If the ashfall is heavy, it can make it impossible to breathe.
Lava flows are almost always too slow to run over people, but they can certainly run over houses, roads, and other structures. Affects regular life.
Pyroclastic flows are mixtures of hot gas and ash, and they travel very quickly down the slopes of volcanoes. They are so hot and choking that if they catch one, it will kill. They are also so fast, about 100-200 km/hour, that one cannot outrun them. If a volcano known for producing pyroclastic flows looks like it may erupt soon, the best thing for one is to leave before it does.
Some of the good ways volcanoes affect people include producing spectacular scenery and producing very rich soils for farming.
Conclusion:
There are about 1500 potentially active volcanoes worldwide. Volcanoes spew hot, dangerous gases, ash, lava and rock that can cause disastrous loss of life and property, especially in heavily populated areas. Volcanic activities and wildfires affected 6.2 million people and caused nearly 2400 deaths between 1998-2017.
