 Complete the following phrase:  The West Coast of the continental United States makes up part of the Pacific Ring of Fire, an area of heavy tectonic and volcanic activity that is the source of 90 of the worlds earthquakes. The American Northwest sees the highest concentration of active volcanoes in the United States, in Washington, Oregon and northern California along the Cascade Mountains. There are several active volcanoes located in the islands of Hawaii, including Kilauea in ongoing eruption since 1983, but they do not typically adversely affect the inhabitants of the islands. There has not been a major life-threatening eruption on the Hawaiian islands since the 17th century. Volcanic eruptions can occasionally be devastating, such as in the 