Table of Contents
What is the highly explosive magma?
Basaltic eruptions are the most common form of volcanism on Earth and planetary bodies. The low viscosity of basaltic magmas inhibits fragmentation, which favours effusive and lava-fountaining activity, yet highly explosive, hazardous basaltic eruptions occur.
What makes magma more explosive?
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. If magma moves slowly toward the surface, gases in the magma have more time to escape.
What is the most explosive volcano type?
Stratovolcanoes are considered the most violent. Mount St. Helens, in Washington state, is a stratovolcano that erupted on May 18, 1980.
What makes a volcanic eruption explosive?
A volcano’s explosiveness depends on the composition of the magma (molten rock) and how readily gas can escape from it. As magma rises and pressure is released, gas bubbles (mainly of water vapor and carbon dioxide) form and expand rapidly, causing explosions.
What type of volcanoes have explosive eruptions?
Composite volcanoes are tall, steep cones that produce explosive eruptions.
What properties of magma favor an explosive volcanic eruption?
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.
Is andesitic magma an explosive?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesite magma can also generate strong explosive eruptions to form pyroclastic flows and surges and enormous eruption columns. Andesites erupt at temperatures between 900 and 1100 ° C.
What determines the explosiveness of a volcano?
The amount of dissolved gas in the magma provides the driving force for explosive eruptions. The viscosity of the magma, however, is also an important factor in determining whether an eruption will be explosive or nonexplosive.