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Eruptions with gas-rich, silica-rich magma are explosive. Instead of producing lava flows, these eruptions produce clouds of hot ash, pumice, and gas. Some ash and gas may be carried miles into the sky in a towering eruption column and then will rain down on the surrounding area. Denser clouds may race down the sides of the volcano as unsurvivable pyroclastic flows, destroying everything in their path. Explosive eruptions such as this are generally the deadliest.
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Does silica or water have the greater effect on the eruptive force of the volcano?
Water gas a greater influence. Regardless of the amount of silica present, an eruption cannot be explosive if there is no gas present, and the chief gas is water vapor. Magma that is high in silica but low in gas content will be slowly extruded to form a lava dome or a very thick lava flow.
Identify and explain the 3 factors that effect the force of a volcanic eruption?
The silica content effects the force of a volcanic eruption because magma with a lot of silica is thicker and magma with less silica is thinner. The amount of dissolved gases in magma effects the force of a volcanic eruption because the less gas in the magma, the less pressure will be inside the volcano. The temperature of the magma effects the force of a volcanic eruption because the hotter the magma, the more runny it is.
What type of lava flow was mount st Helens?
Dacite, a volcanic rock with about 65% silica. This amount of silica in dacite is a lot higher than the basalts of Hawaii which have less than 50% silica. The high silica content makes the magma "sticky" and can cause more pressure to build up. With so much pressure, eruptions from Mount St. Helens can be very violent like the famous 1980 eruption.
What is the meaning of violent eruption?
Violent eruptions (like Mt. St. Helens) have "felsic" magma/lava that is lower temperature (making it thicker), more gas (making it more explosive), and more silica (making it thicker).
What determines if a volcano will have a violent eruption or a quite eruption?
What makes a volcano erupt violently or quietly actually depends on the type of magma inside of it. The magma in volcanoes have different compositons from each other. magmas are sometimes classified by their silica content, which determines how viscus they are (how fluid they are). The more silica the lava has in it, the more thick it is. In very fluid or basaltic lavas, the silica content is around 50%. On the other end of the scale are granitic magmas that have a very high silica content (90%). when a volcano containing fluid magma erupts, the gas within the lava is easily relased, resulting in lava fountains like hawai'i's Kilewea. In a volcano that contains thick, granitic magma, the gases within the lava are trapt inside of it until the eruption lets the gases out, resulting in a violent, distructive explosion such as Mt St Helens.
Does silica or water have the greater effect on the eruptive force of the volcano?
Water gas a greater influence. Regardless of the amount of silica present, an eruption cannot be explosive if there is no gas present, and the chief gas is water vapor. Magma that is high in silica but low in gas content will be slowly extruded to form a lava dome or a very thick lava flow.
Why do volcanic eruptions differ?
The main cause of differences in volcanic eruption characteristics is due to the viscosity of the magma. High viscosity magmas are high in sticky silica which traps gas and produces explosive eruptions. Low viscosity magmas are low in silica and produce eruptions with far less energetic characteristics.
What type of eruption produces a viscous magma containing 53 percent silica and a gas content of 2 percent?
Basaltic
Identify and explain the 3 factors that effect the force of a volcanic eruption?
The silica content effects the force of a volcanic eruption because magma with a lot of silica is thicker and magma with less silica is thinner. The amount of dissolved gases in magma effects the force of a volcanic eruption because the less gas in the magma, the less pressure will be inside the volcano. The temperature of the magma effects the force of a volcanic eruption because the hotter the magma, the more runny it is.
What type of lava flow was mount st Helens?
Dacite, a volcanic rock with about 65% silica. This amount of silica in dacite is a lot higher than the basalts of Hawaii which have less than 50% silica. The high silica content makes the magma "sticky" and can cause more pressure to build up. With so much pressure, eruptions from Mount St. Helens can be very violent like the famous 1980 eruption.
What is the meaning of violent eruption?
Violent eruptions (like Mt. St. Helens) have "felsic" magma/lava that is lower temperature (making it thicker), more gas (making it more explosive), and more silica (making it thicker).
What determines if a volcano will have a violent eruption or a quite eruption?
What makes a volcano erupt violently or quietly actually depends on the type of magma inside of it. The magma in volcanoes have different compositons from each other. magmas are sometimes classified by their silica content, which determines how viscus they are (how fluid they are). The more silica the lava has in it, the more thick it is. In very fluid or basaltic lavas, the silica content is around 50%. On the other end of the scale are granitic magmas that have a very high silica content (90%). when a volcano containing fluid magma erupts, the gas within the lava is easily relased, resulting in lava fountains like hawai'i's Kilewea. In a volcano that contains thick, granitic magma, the gases within the lava are trapt inside of it until the eruption lets the gases out, resulting in a violent, distructive explosion such as Mt St Helens.
If the magma of a volcano has a high amount of dissolved gas what type of eruption will the volcano have?
Typically, high viscosity, high gas magma results in a Plinian (explosive) eruption. The gas pulverizes the magma into ash and may form lateral pyroclastic flows.
Why silica is a gas?
Silica is not a gas. It is a solid at room temperature.
Why do some volcanoes erupt ash and others lava?
The style of the volcanic eruption is very dependent on the amount of dissolved gas that is in the magma (liquid rock below the surface). If there is a high gas content the volcanic eruption will be explosive and create a log of ash. If the gas content is low the eruption produces more lava flows. An example of a high gas content eruption was the last major eruption of Mt. St. Helens in 1980. An example of a low gas content eruption would be the Hawaiian volcanoes.
What are two reasons that magma with a high silica content tend to cause explosive eruptions?
Magma with a high silica content tend to cause explosive eruptions because it has a stiff consistency and blocks the vents. When magma pushes from behind it more pressure happens which means the eruption will be explosive. It also prevents gas and water vapor from getting out. The gases will expand until it explodes.
Why are magmas with high silica content dangerous?
High-silica magmas are extremely viscous, and so tend to trap a large amount of gas under pressure. When such magma erupts, it does so explosively.
