Are explosive volcanoes high or low viscosity?
Explosive eruptions are favored by high gas content and high viscosity (andesitic to rhyolitic magmas). Explosive bursting of bubbles will fragment the magma into clots of liquid that will cool as they fall through the air.
What volcanoes have high viscosity?
Classic examples of shield volcanoes are Mauna Kea and Mauna Loa in Hawaii, as well as Olympus Mons on Mars. When lava has a high viscosity, it’s very thick and doesn’t flow very well at all. Instead of rivers of lava, you can get crumbling piles of rock flowing down hill.
What type of volcano has low viscosity?
Shield volcanoes
Shield volcanoes Where a volcano produces low viscosity, runny lava, it spreads far from the source and forms a volcano with gentle slopes: a shield volcano. Most shield volcanoes are formed from fluid, basaltic lava flows. Mauna Kea and Mauna Loa are shield volcanoes.
How does viscosity affect the explosiveness of a volcano?
The viscosity of the magma, however, is also an important factor in determining whether an eruption will be explosive or nonexplosive. A low-viscosity magma, like basalt, will allow the escaping gases to migrate rapidly through the magma and escape to the surface.
Which lava has the highest viscosity?
The magma that has the highest viscosity is rhyolitic magma.
Why does more viscous magma produce more explosive volcanoes?
How does viscosity affect volcanic eruptions?
Ultimately, the viscosity of a magma will determine the shape a volcano takes over continued eruptions. A magma’s silica content will not only control the rock type that forms, it also controls the relative viscosity of the magma. Differences in a magma’s viscosity will determine the shape a volcano takes.
What effect does viscosity have on how explosive a volcanic eruption is?
Overall, viscosity in a volcano’s magma determines the amount of force required to fragment or break through magma. The more viscous a volcano’s magma, the better conditions are for a violent eruption. The time allowed for degassing also ties into the violent nature of many eruptions.
How does viscosity of pyroclastic materials affect the flow of lava during volcanic eruptions?
Pyroclastic Material If the magma has high gas content and high viscosity, the gas will expand in an explosive fashion and break the liquid into clots that fly through the air and cool along their path through the atmosphere.
What is the effect of the magma’s viscosity on volcanic eruption?
Viscosity combines with other factors to determine how explosive magma will be. For example, small crystals in the magma help gases escape. More crystals in the magma enable more gas bubbles to form, and so they make an eruption more explosive. The rate at which pressure is reduced also affects the explosiveness.