By Justin Lampert and Jenna Macchione

• The United States ranks third in the number of historically active volcanoes.

• Of the 1,500 volcanoes that have erupted in the past 10,000 years, 10 percent are located in the United States.

Where do they exist?

• Hot spots for volcanoes in the U.S. are found in the Aleutian Islands, the Alaska Peninsula, the Hawaiian Islands, and the Cascade Range.

• The majority of active and inactive volcanoes are found in the western part of the U.S. The eastern United States has been isolated from volcanoes due to global plate tectonic features, tectonic plate boundaries, and hot spots in the mantle, which are the causes for volcanic activity

Hawaiian Volcanoes

• The islands of Hawaii were formed by volcanoes. These volcanoes are ideal for scientific research because they erupt frequently but are generally non-explosive.

• Mauna Loa is one of the world’s largest active volcanoes. Since 1900, it has erupted 15 times, with eruptions lasting as long as 145 days to less than 1 day.

Cascade Volcanoes• The Cascade Range is a popular

area for volcanic activity. Although this area has fewer eruptions compared to the volcanic activity in Hawaii, these volcanic explosions have been more catastrophic due to the behavior of the volcanoes and the heavily populated areas in Washington, Oregon, and California. In 1980, the deadly eruption of Mount St. Helens proves this point

• Mount Rainier has not produced a significant eruption in the past 500 years, but is considered by scientists to be one of the most hazardous volcanoes in the Cascades

Alaskan Volcanoes• Alaskan volcanoes have

produced one or two eruptions per year since 1900.

• The most recent eruption was the eruption of 1912 at Novarupta in the Katmai National Monument

• The biggest concern of the people is eruptions that could affect the Cook Inlet Region which is 60% of the Alaskan Population

Augustine, Cook Inlet, Alaska

March 27, 1986

Restless Calderas

• When large volume of magma is removed from beneath a volcano, the ground subsides or collapses into the emptied space, to form a huge depression called a caldera.

• Most caldera unrest does not lead to an eruption, however, the possibility of the violent eruptions causes scientists to monitor some of the active calderas today.

Medicine Lake, California

Most Recent Eruption

• 18 May, 1980 Mt St Helen’s, Southwest Washington State

• Prior to eruption: Small craters projecting steam explosions and ash

• After eruption: Magma and lava created dome over the crater

The End