Introduction
Ascending eruption cloud from Redoubt Volcano near Cook Inlet, Alaska
in April, 1990 (J. Warren—USGS)
When people think of geology, they often immediately think of volcanoes. Volcanoes, along with earthquakes, let us know that the earth is "alive" and that its landscape is slowly changing over time. As you learned earlier, volcanic activity is often connected to plate tectonics. In this section, you will discover why volcanoes happen and how they work.
Volcanoes are much more than lava! Volcanoes erupt numerous types of earth materials and can cause a chain reaction of dangerous events with other earth processes. Moreover, much of a volcano's activity actually occurs below the ground. In this module, you'll learn to classify a volcano based on the type of material it erupts. Additionally, you'll discover the risks associated with volcanic eruptions.
Equipped with this information, you will learn the three different styles of volcanic activity and take a look at examples of each kind. Once you know how they work, you can understand why Alaska has many volcanoes whereas Indiana hasn't had a volcano for over 500 million years. We'll finish with a look at a few case studies of past volcanic eruptions.