Various factors trigger a volcanic eruption. The three predominant factors are the magma's buoyancy, the pressure from the gases that separate in the magma and the merger of a new batch of magma with a chamber already filled with magma.
The melting of rock inside the earth produces a melt with more volume than the rock but the same mass. This melt is less dense than the rock that surrounds it. The lighter magma moves upward because of its buoyancy, and if the density between the surface and zone of its generation is less than the overlying and surrounding rocks, it erupts.
A few magma compositions contain dissolved volatiles such as water and carbon dioxide. The amount of gases dissolved in the magma is zero at atmospheric pressure, but it increases with an increase in pressure. In andesitic magma, which is saturated with water, the solubility of water decreases as the magma moves upward, and the water separates from it in the form of bubbles. When the volume of bubbles in the magma reaches about 75 percent, disintegration of magma into partially solid and molten fragments happens, along with an explosive eruption. Injection of more magma inside an already filled magma chamber forces some of the magma to move toward the surface, causing an eruption..Learn More
Hot melted rocks collect under the Earth's surface and when the pressure becomes too hard, the Earth's skin breaks, and a volcano erupts. The melted rock inside the Earth is called magma, but when it comes out in an eruption, it is called lava.Full Answer >
Volcanologists wear heavy boots, long-sleeved shirts and heavy work gloves in order to protect their bodies from lava near a volcano. According to Oregon State University, volcanologists might also wear jeans, a rock-climbing helmet for protection and a gas mask.Full Answer >
The inside of a volcano has one or more vents through which gas and lava flow during eruptions. Below the vent is the magma, which is the molten rock that flows upward due to the divergence or convergence of tectonic plates in the Earth's crust. The number of vents and shape of the buildup of magma inside the magma chamber depends upon the type of volcano.Full Answer >
Oshima as an island stratovolcano with a large caldera on its summit. Stratovolcanoes are conical volcanoes built up by many layers of hardened lava and volcanic ash, with steep profiles and periodic eruptions.Full Answer >