Types of eruptions
Geologists classify volcanic eruptions as either quiet or explosive.
Quiet Eruptions
An eruption is quiet if the magma has LOW amounts of silica. Low-silica magma is not very viscous, so it flows out easily and gently. Quiet eruptions can produce both pahoehoe and aa. Quiet eruptions are what formed the Hawaiian islands. Explosive Eruptions An eruption is explosive if the magma has HIGH amounts of silica. High-silica magma is very viscous. This makes it thick and sticky, which can clog up the pipe. The trapped gases build up pressure until the volcano explodes and pushes out the magma with great force. |