Volcanic eruptions range from mild to violent. When volcanoes erupt, the materials left behind provide information to scientists studying the Earth’s crust.
- Mild, or non-explosive eruptions, produce thin, runny lava that is dark in color, and low in light colored minerals called silica. During non-explosive eruptions, lava simply flows down the side of the volcano. Shield volcanoes produce these types of eruptions.
- Explosive eruptions, on the other hand, are gassy and do not produce much lava. Instead, the violent explosions hurl ash, and debris into the air. The materials left behind are light in color and high in light colored minerals called silica. Cinder cone volcanoes produce these types of eruptions. These materials help geologists determine the composition of the crust underneath volcanoes. Some volcanoes have both types of eruptions, and they are known as composite or strato-volcanoes.
