Plume shape illustrations for different types of eruptions

A weak plume typically forms above small eruptions such as the April-May 2010 eruption of Eyjafjallajokull volcano, Iceland. A strong plume with a major umbrella cloud forms during very large eruptions, such as Pinatubo on June 15, 1991. During superuruptions, such clouds may push their way hundreds or thousands of kilometers upwind.