Factors Affecting Magma Viscosity
* Temperature: Higher temperatures make magma less viscous. Think of honey: it's thick (viscous) when cold, but runny when heated.
* Composition:
* Silica Content (SiO2): The higher the silica content, the more viscous the magma. Silica-rich magmas, like those found in rhyolite, are very thick and sticky.
* Water Content: Water dissolved in magma lowers viscosity. This is because water molecules disrupt the bonding between silica tetrahedra.
* Dissolved Gases: Gases like water vapor and carbon dioxide can lower viscosity, especially at high pressures.
* Crystal Content: As magma cools and crystallizes, the crystals act as obstacles, increasing viscosity.
Answer:
The factors that cause magma to be *less viscous* are:
* Higher temperature: Heat breaks down the bonds between molecules, making the magma flow more easily.
* Higher water content: Water molecules interfere with the bonding of silica, making the magma less viscous.
* Dissolved gases: Gases can also disrupt the bonds between silica molecules, reducing viscosity.
Important Note: It's also worth mentioning that lower silica content can lead to less viscous magma. Magmas with lower silica content, like basalts, are often thinner and more fluid.
