A volcano is a vent or chimney that, through eruptions, transports molten rock (known as magma) from depth to the Earth’s surface. Lava is magma that erupts from a volcano. it accumulates around the vent, forming a cone. If a volcano is erupting lava, releasing gas, or causing seismic activity, it is currently active. An active volcano is classified as dormant if it has not erupted in a long time but may do so in the future. A volcano is considered extinct when it has been dormant for more than 10,000 years. Volcanoes can be dormant or inactive for hundreds or thousands of years before erupting again. During this time, they may become obscured by vegetation, making identification difficult. Follow PowerPAc plus to learn more!!
What is Volcano?
A volcano is a crack in the earth’s crust that allows lava, volcanic ash, and gasses to escape. Volcanic eruptions are partially driven by dissolved gas pressure, similar to how escaping gasses force the cork out of a bottle of champagne. Liquid magma containing dissolved gasses rises through cracks in the Earth’s crust beneath a volcano.
Shape of magma
Volcanoes have a variety of shapes that are determined by the composition of the magma and the nature of the eruption. When a volcano produces very fluid lava (lava with a low concentration of the compound SiO2, or silica), the magma flows a long distance before cooling, resulting in a flat, shield-shaped volcano. When a volcano produces very sticky magma (high in silica), it tends to erupt in an explosive manner, with lava, pyroclastic flows, and ash. This material accumulates all around the volcano, forming a steep cone, which is a typical volcano shape. Volcanoes formed from ash and cinders typically have steep sides, but they erode faster than volcanoes formed from lava.
Type of Tornado
The importance of viscosity in volcanology cannot be overstated. Highly viscous (very sticky) magma produces steep-sided volcanoes with slopes of 30–35°. Because the viscous volcanic material does not flow far from where it erupted, it accumulates in layers, forming a cone-shaped volcano known as a stratovolcano. Shield volcanoes, on the other hand, have less than 10° slopes and erupt more fluid lavas known as basalt. When a shield volcano erupts, basalt can flow for long distances away from the vent, resulting in broad, gentle slopes.
When a volcano spews low viscosity, runny lava, it spreads far from the source, forming a shield volcano with gentle slopes. The majority of shield volcanoes are formed by fluid basaltic lava flows. The shield volcanoes Mauna Kea and Mauna Loa are located in Hawaii. They are the world’s largest active volcanoes, rising over 9 km above sea level around the Hawaiian island of O’ahu.
Stratovolcanoes have steeper sides and a more cone-like shape than shield volcanoes. They are formed by viscous, sticky lava that is difficult to flow. As a result, It accumulates around the vent, forming a volcano with steep sides. Because of the gas buildup in the viscous magma, stratovolcanoes are more likely to produce explosive eruptions.
Andesite (named after the Andes Mountains) is the most common rock type erupting from stratovolcanoes, but stratovolcanoes erupt a diverse range of rocks in a variety of tectonic settings.
On the Caribbean island of Montserrat, the Soufrière Hills volcano is well known for its lava dome complex at the summit, which has gone through phases of growth and collapse. Because viscous it is not very fluid, it cannot easily flow away from the vent when extruded. Instead, it accumulates on top of the vent, forming a large dome-shaped mass of material.
A magma chamber is a chamber beneath a volcano that stores magma. When a large, explosive eruption occurs, the roof of the magma chamber can collapse, forming a depression or bowl with very steep walls on the surface. These are calderas, which can span tens of miles. Calderas can also form as a result of an eruption that destroys the summit of a single stratovolcano. Caldera-forming eruptions can annihilate big sections of a single stratovolcano.
Why does Volcano form and erupt?
The tectonic plates are in contact, but they are also moving relative to one another. Fault movement at plate boundaries can provide a convenient path for magma to reach the surface. This is best explained by examining the three main types of plate boundaries:
- Constructive boundaries (divergent): where plates are moving away from each other due to the formation of new crust between the two plates
- Destructive boundaries (convergent): where plates are moving in the same direction and old crust is either dragged down into the mantle at a subduction zone or pushed upwards to form mountain ranges.
- Transform boundaries (conservative): where plates move past each other but no crust is created or destroyed
There are three settings where volcanoes typically form:
- constructive plate boundaries
- destructive plate boundaries
- hot spots
Volcanoes are not usually found at transform boundaries. One of the reasons for this is that at the plate boundary, there is little or no magma available.
How to escape from Volcano?
If a lahar, pyroclastic flow, or lava flow is headed toward you
- Leave the area right away. If you are advised to evacuate due to an impending eruption, do so.
- If you have the option of driving rather than walking, do so. Keep doors and windows closed while driving, drive across the path of danger if possible or away from it if you can’t, and keep an eye out for unusual road hazards.
If you are indoors
- All windows, doors, and fireplace or wood stove dampers should be closed.
- Turn off all fans, heaters, and air conditioners.
- Bring animals and pets into closed shelters.
If you are outdoors
- Seek refuge indoors.
- Roll into a ball if you get caught in a rockfall to protect your head.
- If you live near a stream or river, keep an eye out for rising water and possible mudslides in low-lying areas. Move as quickly as possible upslope.
- Seek medical attention for burns as soon as possible. Immediate medical attention can save a person’s life.
- If volcanic gases and fumes irritate your eyes, nose, or throat, get away from the area right away. When you are no longer exposed to the gases or fumes, your symptoms should subside. Consult your doctor if the symptoms persist.
Protecting yourself during ashfall
- If possible, stay inside with the windows and doors closed.
- Long-sleeved shirts and long pants are required.
- To protect your eyes, wear goggles.
- If ash is constantly falling, you may not be able to stay indoors for more than a few hours because the weight of the ash could collapse your building’s roof and block air intakes. When an ashfall lasts more than a few hours, follow the advice of authorities and leave the area.
- Turn off your car or truck’s engine. Avoid driving in areas where there has been a lot of ashfall. Driving stirs up ash, which can clog engines and cause vehicles to stall. If you must drive, keep the windows up and turn off the air conditioning system. When the air conditioning system is turned on, outside air and ash are drawn in.
5 most dangerous Volcano in the World
Mount Rainier is one of the most dangerous volcanoes in the United States for a variety of reasons. Mount Rainier’s high elevation, chemical composition, proximity to Washington’s Seattle and Tacoma suburbs, and the volcano’s ability to produce intense pyroclastic flows, lava flows, and volcanic ash are all cited by the USGS. The heat from Mount Rainier’s lava flows has the potential to melt the volcano’s snow and ice, resulting in a rapid downstream flow of mud, rocks, and debris known as lahar. According to the USGS, the most dangerous risk posed by an eruption at Mount Rainier is massive lahars. According to the Global Volcanism Program, it would affect more than two million people.
Mount Pinatubo, situated in a populated region of the Philippines, became notorious after a 1991 major eruption that was the second largest thing of the twentieth century, closely following Novarupta. While Pinatubo did not have a history of explosive eruptions prior to the eruption, the 1991 event killed at least 722 people after producing pyroclastic flows that formed a lake-filled caldera in the volcano. Today, more than 21 million people live within 100 kilometers (about 62 miles) of Pinatubo, according to the Global Volcanism Program.
Mount St. Helens’ 1980 eruption was the deadliest and most destructive volcanic event in US history. It killed 57 people and thousands of animals, and it destroyed approximately 200 square miles of forest. The USGS reports that Mount St. Helens’ history of explosive eruptions indicates that future episodes are highly likely. According to the USGS, another explosive eruption would cause big amounts of ash to fall across the Pacific Northwest, and the volcano is being closely monitored.
According to a report from Oregon State University’s Volcano World program, Japan’s famous Mount Fuji has not erupted since 1707, when a major earthquake earlier that year likely triggered it. Following the 9.0-magnitude earthquake that struck Japan in 2011, experts warned that Fuji was at risk of another eruption in 2014. According to researchers, the earthquake increased the pressure beneath Mount Fuji. The 1707 eruption emitted ash and debris into the atmosphere, which reached Tokyo. According to the Global Volcanism Program, if Fuji erupts again, more than 25 million people in the surrounding area could be affected.
Mount Merapi, one of Indonesia’s most active volcanoes, has been erupting for centuries. According to NASA, the most dangerous aspect of Merapi is pyroclastic flows, which can spread over large areas and endanger people. Merapi erupted again on May 11, sending plumes of smoke into the air and forcing evacuations from the densely populated region — the surrounding area is home to more than 24 million people, according to the Global Volcanism Program.