Many different substances are expelled through a volcano during an eruption; these can be gaseous, solid, liquid, and/or semi-fluid. These eruptions occur during volcanic activity due to the high temperatures and pressures within the Earth. Volcanism is the phenomenon, or set of geological phenomena, that occur from the formation of magma and its emergence to the surface.
In this article we are going to tell you everything you need to know about volcanism, its characteristics and importance.
what is volcanism
Volcanic activity is created by the movement of heavy matter into the Earth's interior . This matter exerts pressure on the fluid rocks of the mantle, pushing them toward the surface. The field of study that deals with the physical and chemical phenomena of volcanic activity is called volcanology . It is a branch of geology that analyzes volcanoes, springs, fumaroles, eruptions, magma, lava, pyroclastic or volcanic ash, and other activities related to volcanic activity.
Volcanism is a geological phenomenon. It primarily affects vulnerable areas of the Earth's crust, where magma flows from the lithosphere to the surface. Volcanic activity involves a physicochemical state , expressed through microseisms and eruptions, which can range from large-scale events to simple fumaroles.
Depending on the type of activity, volcanic activity is called an eruption, explosion, or hybrid. The effusive is characterized by the calm discharge of lava and gas. Explosives pass through violent and destructive discharges. The mixed is alternating soft and explosive eruptions.
There is an octave scale of the Volcanic Eruption Index, which experts use to measure the extent of a volcanic eruption. This takes into account the products of the volcanic eruption: lava, pyroclasts, ash, and gases. Other factors include the height of the eruptive plume and the injected tropospheric and stratospheric emissions. On the scale, 1 indicates slight intensity; 2, explosive; 3, violent; 4, catastrophic; 5, cataclysmic; 6, colossal; 7, super-colossal; and 8, apocalyptic.
How is it formed?
Volcanism is caused by the high temperatures and pressures within the Earth. The movement of lava in the mantle is driven by thermal convection. Ocean currents, along with gravity, drive the continuous movement of tectonic plates and, more sporadically, volcanic activity.
Magma reaches the Earth's surface through volcanoes located at the boundaries and/or hot spots of tectonic plates. Its behavior on the surface depends on the consistency of the magma in the mantle. Viscous or thick magma can cause volcanic eruptions. Liquid or invisible magma produces eruptive volcanism, throwing large amounts of lava to the surface.
What types are there?
The general classification distinguishes two types of volcanoes: primary and secondary. Primary volcanism is further divided into central and fissure types. The former emerges through the crater, while the latter emerges through cracks or fissures in the Earth's surface. Secondary volcanism occurs in hot springs, geysers, and fumaroles.
Another classification focuses on the path of the magma that rises from the interior of the Earth to the surface. According to this, there are two types of volcanism: intrusive or subvolcanic and eruptive, in which the erupted rock reaches the earth's surface.
What is intrusive volcanism?
Intrusive volcanism is the movement of magma within the Earth's crust . During this process, molten rock cools and solidifies between rock formations or layers without reaching the surface.
Subvolcanic phenomena are responsible for the formation of dikes, shallow marine rocks, and solid rock formations called laccoliths. They also form the basis of foundations, parapets, and nappes. Most dikes are deposited in a single event. Some shrink and weaken as they cool, undergoing multiple magma injections. They are classified as composite or layered depending on the type of rock they are composed of.
submarine volcanism
Submarine volcanism is caused by oceanic volcanoes. Underwater, gases and lava behave similarly to terrestrial volcanoes. However, it differs from terrestrial volcanoes in that it releases large amounts of water and mud. Submarine phenomena help form small islands in the middle of the ocean , some permanent and others that gradually disappear under the action of the waves.
It occurs mainly at mid-ocean ridges and other areas where tectonic movement is high, where plates pull apart to form geological fissures or faults. The ejected lava sticks to the edges, helping to spread out the seafloor.
What are the consequences of a volcanic eruption?
Volcanic activity can trigger eruptions, earthquakes, hydrothermal vents, and volcanic winters. Gas and ash emissions are detrimental to Earth's climate and contribute to climate change. They pollute the air in the area near the volcano and spread to forests and farmland through rainfall. The effect is not always negative, however, and sometimes the deposited ash is rich in minerals, making the soil more productive.
Although not as frequent as earthquakes and extreme weather events, volcanic activity can be devastating. When it occurs near the sea, it can produce tremors, landslides, fires, and even tsunamis. It endangers the lives and property of people living in volcanic areas.
About 1.000 people die each year in volcanic disasters, according to the United Nations disaster relief organization. The main reasons are pyroclastic flows, mudflows, tsunamis or tides. Many others were affected by emissions of toxic gases and ash.
Importance of volcanism
Volcanism leads to rock formation. The released magma cools and solidifies in several stages and over varying periods. The rate at which it cools determines the formation of rock types such as basalt, obsidian, granite, or gabbro. Rocks in contact with the magma may melt with it or be affected by contact metamorphism.
Humans have used volcanic rocks and the metals they contain since ancient times. Today, they are used as raw materials for the production of construction materials, such as gravel and volcanic sand. They are also used in the telecommunications industry as components in the manufacture of mobile phones, cameras, televisions, and computers, including vehicles.
Volcanic activity also enables the formation of aquifers and springs, and is an excellent source of geothermal energy , which can be used to generate electricity and heat. In some countries, volcanoes, hot springs, and volcanic mud deposits are promoted as tourist attractions based on their geological features. This generates considerable economic income for the surrounding communities.
I hope that with this information you can learn more about volcanism and its characteristics.