Causees of Volcanic Activity

394 Words2 Pages
What causes volcanic activity? An eruption begins when pressure on a magma chamber forces magma up through the conduit and out the volcano's vents. When the magma chamber has been completely filled, the type of eruption partly depends on the amount of gases and silica in the magma. The amount of silica determines how sticky (level of viscosity) the magma is and water provides the explosive potential of steam. A volcano can be defined as a fissure in the crust of the earth erupting gases and molten lava. Volcano is a vent through which magma and dissolved gases are discharged. Magma forms when lower crust or the upper mantle of the earth melts and this magma is discharged in volcanic eruption. The cause of eruptions may be from a combination of events. Large continental landmasses are in motion because of convection currents and magma currents circulating in the planet's molten core. Where two landmasses meet there are two possibilities. They will either buckle in an upward direction the result being impressive mountain ranges, or one may begin to slowly slide beneath the other. This process is slow and occurs over periods of many thousands of years until the pressure builds enough to fracture the hard crust. This in turn allows the release of magma and hot gas once the pressure is sufficient to breach the hard crust. Hot lava, gasses and fine particles then discharge over a wide area. Gasses and dust billow upwards to the stratosphere and the lava flows can cover hundreds of square miles. Volcanic eruption is caused by three major factors: The first is buoyancy of the magma formed in the crust of the earth. When rocks melt in the crust of the earth forming magma, its mass remains the same, whereas the volume increases considerably. This magma rises towards the surface due to its buoyancy. The second factor is the pressure from the gases in the magma. Molten
Open Document