What happens when a volcano erupts | Damage caused by volcanoes
definition of volcanoes.
Volcanoes: are the places from which molten rocks (magma) emanate from the earth's interior to settle on the outer surface of the earth's crust. Volcanoes are found in areas where there is a high supply of lava, where most active volcanoes are located near the margins of the plates that make up the Earth's crust, and there are exceptional volcanoes called hot spot volcanoes, such as the Mauna Loa Hot Spot in Hawaii that rises over gatherings of magma called molten blades. The eruption of volcanoes results in various outbursts. Some volcanoes spew ash and gases, some spew crushed rocks, and others spew a torrent of destructive mud that causes avalanches.
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| Damage caused by volcanoes |
How does a volcano erupt happen?
Magma is formed in the earth’s interior as a result of pressure and heat, and because magma is less weight and density than solid rocks in the earth’s crust, it rises to the top towards the surface, and during its ascent it causes the fragmentation of some types of rocks several kilometers from the surface of the earth’s crust because of its very high temperature, which leads To the formation of cavities known as the "magma chamber", where the magma rising to the top gathers. Over time, magma makes its way to the outer surface through cracks, faults, weak parts of rock, and grooves formed by the convergence and divergence movements of the plates; That is why we find that 90% of volcanoes around the world are concentrated at the edges of the plates, while other volcanoes are formed in areas of hot spots that are formed as a result of the movement of thermal currents rising from the ground, which gradually leads to the melting of the plate above it and thus the magma rushes out.
Events associated with volcanic eruptions
The occurrence of a volcanic eruption is accompanied by many different events and risks, which may directly or indirectly affect the surrounding environment, and we mention the following:
- Lava flows: magma is formed in volcanoes by the melting of rocks in the mantle layer; As a result of the high temperatures dramatically, and the magma resulting from the melting of rocks is less dense than the solid rocks around it, as a result the strong gravitational force pushes the magma to the surface by passing through the cracks, and sometimes the magma may collect in the ground until the appropriate pressure is produced to flow to the surface, and the flow takes two basic forms around the world; Either the flow is smooth, with a smooth surface, or it is viscous, with thick, lumpy piles covering its surface. When the magma reaches the surface, it is called (lava), and it is the most common product of volcanoes, as it is exposed to direct weather conditions to cool and form volcanic rocks. Volcanic rocks are divided into four main types: basalt, andesite, dacite, and rhyolite.
- Volcanic eruptions: Mega volcanic eruptions occur when there is a rapid expansion of gases in the Earth's interior, as a result of a sudden drop in pressure of the thermo-hydraulic system at a distance, or due to the rapid mixing of magma and groundwater. During a volcanic eruption, a scattering of lava and rocks occurs, and is accompanied by emissions of ash, blocks and hot fragments, which may reach tens of kilometers into the atmosphere, and these emissions can be classified according to their size, where the size of the ash is close to the size of rice grains, and the size of the hot fragments ranges from 2 mm to About 64 mm, and masses of more than 64 mm in size are called volcanic blocks or bombs, and the intensity of the volcanic eruption can be determined by knowing the amount of emitted gases, the degree of viscosity of magma and its mineral composition.
- Pyroclastic flows: Also called avalanche avalanches or ash flows, this is the most dangerous event that may occur when a volcano erupts. Pyroclastic flows differ from each other in size and type, but they share a fluid layer of deadly volcanic particles, trapped air particles. And explosive gases, and these flows are characterized by high temperatures ranging between 100 and 700 degrees Celsius, which leads to melting everything that gets in their way, and is characterized by a large flow speed that may reach 160 km per hour.
- Gas clouds: The eruption of volcanoes may produce clouds of suffocating or toxic gases such as carbon dioxide, carbon monoxide, hydrogen sulfide, and sulfur dioxide, which lead to pollution of lakes, death of animals and damage to vegetation, and one of the most common volcanic gases is water vapor. There are also small amounts of other volatile elements and compounds, such as hydrogen, helium, nitrogen, hydrogen chloride, hydrogen fluoride, and mercury. Volatile gases can be determined by knowing the amount of oxygen in the volcanic environment. When oxygen is lacking, the elements methane, hydrogen, and hydrogen sulfide are chemically stable. When hot volcanic gases mix with atmospheric gases, water vapor, carbon dioxide, and sulfur dioxide are elements stable.
- Ash fall: As volcanic particles continue to erupt upwards during volcanic eruptions, high ash clouds resulting from the lava flow fall, as they accumulate on the surface of the earth with a thickness of a few centimeters, and ash fall may cause damage to plants, and can cause starvation and disease in poor countries. . Despite this, the decomposition of nutrient-rich volcanic ash creates the best soils in the world.
- Avalanches, tsunamis and mudflows: Avalanches occur as a result of volcanic eruptions by turning rocks into mud due to hydrothermal activity, and these avalanches may lead to a tsunami as a result of a sudden eruption of ice in the water. Mudflows occur when valleys near the volcano are flooded with water mixed with ash, or hydrothermal mud.
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