A volcano is a landform (typically a mountain) where molten rock erupts from the planet's surface. A volcano is a mountain that opens downhill to a pool of molten rock (magma) under the earth's surface. It is a crater in the ground when molten rock and gas erupt. The word comes from the Latin word vultus, meaning "face," because the appearance of a newly formed volcano is very similar to that of someone smiling or laughing.
There are three main types of volcanoes: stratovolcano, shield volcano, and composite volcano. A stratovolcano has a flat top with no more than 200 meters (660 feet) of elevation change; otherwise it is called a mountain volcano. A shield volcano has a steep-sided bowl with an almost level floor; there may be a small amount of lava on the floor of the bowl. A composite volcano has elements of both a stratovolcano and a shield volcano.
Stratovolcanoes usually arise quickly after an island collapses into a caldera. They often reach great heights and have extremely rugged surfaces. Shield volcanoes take longer to build up but they can be just as high and have equally rough surfaces. Composite volcanoes are combinations of the other two types of volcano. They tend to be lower than either of the other two types but still much higher than a field.
A volcano is a mountain that opens downhill to a pool of molten rock under the earth's surface. Gases and rock surge up through the aperture during an eruption, spilling over or filling the air with lava particles. Lava flows, hot ash flows, mudslides, avalanches, falling ash, and floods can all result from volcanic eruptions. Volcanoes are responsible for creating most of the Earth's oceans; they form when molten rock pushes its way up through the crust of the planet. The resulting explosions blow away much of the rock above the vent, forming new land.
People have been talking about volcanoes since ancient times. In fact, some scientists believe it was because people wanted to go on adventures that they invented stories about gods who were angry with them. These stories allowed people to explain events they could not understand, such as sudden weather changes or earthquakes. Scientists use this same reason why people report seeing things in the sky that cannot be explained by science: It is easier to say that you saw a god than to admit you were wrong.
In 1783, Laki (pronounced /lak/), a volcano in Iceland, caused by much the same process as others but at a greatly amplified scale, killing many people along with animals and destroying much of the country's agriculture. It has been suggested that this is what caused the great famine in Ireland that year.
Eruptions occur when pressure builds up. Gases and rock surge up through the hole, spilling over or filling the air with lava particles. Volcanoes have been known to destroy whole forests. They can also form new lands by throwing rocks and dust into the air, which then falls back down again. There are several types of volcanoes: shield, stratovolcano, composite, and plugger.
Shield volcanoes are relatively low hills with no more than 300 meters of elevation. They do not reach the height of other volcanic forms but they do cover a large area. The largest shield volcano on Earth is Mauna Loa in Hawaii. Stratovolcanoes are tall mountains with steep slopes covered in vegetation. They contain a central peak called a domesicle. The tallest volcano in this category is Mauna Kea in Hawaii. Composite volcanoes are shaped like shields but they have a core of hardened lava that extends down past the base of the slope. These cores can be anywhere from a few hundred yards to nearly a mile in length. The youngest composite volcano is Pu'u O'Oi in Hawai'i. It is only about 60 years old. Plugger volcanoes are where a piece of rock called a plug jams the opening of a cavity beneath it, preventing any more gas or liquid material from entering or leaving the cavity.
A volcano's danger zone has a radius of around 20 miles. Beyond this zone, there is no evidence of heat or movement at the surface. Volcanoes can be active today without any signs of activity yesterday or tomorrow, but if they were active in the past, they will most likely still be erupting.
Volcanoes can be dangerous because hot gases and rocks can flow down their slopes and destroy everything in their paths. They can also cause death or damage even far from their actual location because the energy they release travels long distances. Volcanoes are important to study because they help us understand how our world was created and they tell us about the history of our planet.
I have learned that volcanoes are very powerful forces that we cannot always see. They can destroy buildings, kill people, and change the environment forever. But they are also interesting to watch because they show us something new every time they erupt.
A volcano is a mountain that now has or has had lava (hot, liquid rock) erupting from a magma chamber beneath the earth. Volcanoes are produced as a result of tectonic plate movement. There are 17 large, hard tectonic plates in the Earth's crust. In its mantle, they float atop a hotter, softer layer. Where two plates meet, they slide past one another and create friction which heats up their outer layers. This heat can cause portions of the crust to break away and rise into the air, forming a volcano.
Volcanoes can be either active or dormant. Active volcanoes are those that have recently erupted. Dormant volcanoes do not show any signs of activity but they may still contain molten rock within their bodies. The location of a volcano's vent is determined by looking at how much smoke, dust, or gas is coming out of it. The color of the rock near the vent usually indicates what type of material the volcano is made of: red for lava, white for snow and ice, black for burned rock, and gray for other types of rock.
People have used volcanoes for communication before they were even aware of electricity. They still do today in remote areas where there are no other options for communication. A good example is Volcano Bay, a tourist destination in Japan with several active volcanoes located within its boundaries. Visitors can take advantage of this fact by writing messages on the rocks with paint, then watching them be carried away by volcanic ash.
A volcano as defined by children. 1: a crack in the earth's crust through which hot or molten rock and steam explode. 2: a hill or mountain created by volcanic ash released during an explosion.
Children's definitions of volcanoes may not be as accurate as you would hope, but they do provide an interesting perspective on the subject. By learning about how children see volcanoes, you will better understand what they are and aren't capable of doing.
The most common form of childhood volcanism is called "tectonics". Tectonics is the process by which plates move over a hotspot creating new mountains. When plates collide, heat is transferred along their boundaries causing them to melt. As the plates cool, they leave behind deep cracks filled with hot liquid rock that explodes out from inside the planet like a geyser.
Volcanoes can also appear out of nowhere without any precursor events. A child-identified volcano is known as a "mythical volcano" or simply a "volcano". These objects arise from thermal vents in the ground, usually near lakes. The vents produce large amounts of carbon dioxide gas which builds up under pressure until it escapes in a violent eruption. Flaming rocks are sometimes thrown into the air by these eruptions.
Finally, there are volcanic islands.