Eruptions can come from side branches or from the top of the volcano. Some eruptions are terrible explosions that throw out huge amounts of rock and ash and kill many people. This is usually caused by gas dissolved in the magma that feeds the volcano. When the magma has little gas, the eruption is usually a quiet outflow of hot lava.
Several more complex types of volcanic eruptions have been described by volcanologists. These are often named after famous volcanoes where that type of eruption has been seen. Some volcanoes may show only one type of eruption during a period of activity, while others may show a range of types in a series.