Thick, viscous magma builds resists eruption more than a thinner, runnier magma. This causes the thick, viscous magma to build up far more pressure which leads to far more violent eruptions.
Shield volcanoes generally have a thinner, runnier magma, which is why their eruptions have longer, less violent cycles, such as Kilauea which has been erupting non-stop since 1983.
Stratovolanoes generally have a thicker, viscous magma which results in incredibly violent, explosive eruptions which eject large masses of rock and ash far up into the air, such as the eruptions of Mt. St. Helens and Krakatoa.
The gasses dissolved in the magma (or the entry of water into the magma) cause the explosive behaviour.
The most likely cause of a volcano is a convergent plate boundary, where one tectonic plate is forced beneath another in the process of subduction. This movement melts rock and generates magma, which can rise to the surface and erupt as a volcano.
Lateral movement of the tectonic plates is the interaction that is the most likely cause of the volcano. The outermost shell of the planet is broken up into tectonic plates.
Lava.lavaThis is known as lava.
No because weather has no affect on the earth mantle and the mantle is the source of magma for the volcano.
A volcano can explode when pressure builds up inside it due to trapped gases and magma. This pressure can be released explosively when the volcano erupts, causing an explosion.
In most cases, no. However, there is evidence that, on a few occasions, earthquakes appear to have triggered eruptions, most likely by disturbing the magma chamber beneath the volcano. Earthquakes often precede a volcanic eruption, be these are not the cause of the eruption, but are rather a result of the movement of magma that leads to an eruption.
The gasses dissolved in the magma (or the entry of water into the magma) cause the explosive behaviour.
The amount of pressure that pushes up the magma in a volcano
There are several reasons. First, there isn't always magma (what lava is called when it is underground). The magma is usually trapped far below the volcano, unless the volcano is erupting or about to erupt. Second, heat alone cannot create an explosion. An explosion requires rapid expansion. Explosive volcanic eruptions occur when gas trapped in the magma is suddenly released as pressure on the magma decreases, or when water flash boils on contact with lava or magma. If there is no gas, and no water, there cannot be an explosive eruption. Third, the kinds of magma most likely to cause explosive eruptions are very viscous, meaning they do not flow very easily. As a result, they tend to get "stuck." Finally, the poper term is "erupt" not "explode" as not all eruptions are explosive. If there is not enough gas the volcano will ooze out lava rather than causing an explosion.
The most likely cause of a volcano is a convergent plate boundary, where one tectonic plate is forced beneath another in the process of subduction. This movement melts rock and generates magma, which can rise to the surface and erupt as a volcano.
Lateral movement of the tectonic plates is the interaction that is the most likely cause of the volcano. The outermost shell of the planet is broken up into tectonic plates.
Lava.lavaThis is known as lava.
the magma moving up will cause a eruption
Magma that hardens in a vent on an active volcano. They trap gasses in the volcano and can sometimes cause violent eruptions.
If the rocks below the volcano melt, the liquid rock will gather in a chamber underground. As the pressure in this chamber increases the magma may be forced out. This is an eruption. Eruptions are more likely to be explosive if the magma contains a large amount of water or gas, as the expansion of the water or gas makes the magma explode as it is released.
basalt