Roughly 40-50% silica content.
Low gas content
Eruption temp = 1100 degrees
Eruption type = flowing
Thin lava flows, forming shield volcanoes.
Examples: Hawaiian Islands chain
60-65% silica content.
Moderate gas content.
Eruption temp = 800-1000 degrees.
Eruption type = flowing and moderatly explosive.
Thick, rubbly lava flows and ash falls. Creating stratovolcanoes.
Examples: Mount Etna, St Helens, Mount Fuji and Nevada Del Ruiz.
Roughly 70% silica content.
Very high viscosity.
High gas content.
Eruption temp = 750-850 degrees
Eruption type = Very explosive
Pumice and ask fall, pyroclastic flows also occur. Lava flows when the magma is low in gas.
Examples: Caldera volcanoes. Such as Yellowstone and Chaiten.
Found at convergent or destructive plate boundaries.
Magmas with high gas content, high silica content and low temperature are viscous and produce explosive, hazardous volcanoes.