75% of Earth’s active volcanoes
Ring of Fire includes both volcanoes and great earthquakes
Ring of Fire volcanoes circle the Pacific Ocean. The horseshoe shaped circle is 40,000 km (25,000 miles) long. It has 452 volcanoes with 75% of the world’s active volcanoes in the circle. Geologists use the term Ring of Fire to describe the volcanoes and great earthquakes around the Pacific Ocean.
Mount Pinatubo on the Ring of Fire, USGS
Volcanoes due to Tectonic Plate movement
Subduction zone volcanoes
The volcanoes in the Ring of Fire are a direct result of plate tectonic movement. The Pacific Ocean is getting smaller as it subducts beneath plates moving toward the Pacific Plate. They form subduction zones around the Pacific Ocean.
Divergent plate boundaries
Other small plates have formed divergent boundaries with the Pacific Plate. These plates are subducting beneath the North American Plate and the South American Plate on the east side of the Pacific Ocean.
Stratovolcano formation
Subduction zones with an overriding plate form stratovolcanoes on the continental side of a subduction zone. These volcanoes form volcanic arcs on the continents like the Andes Mountains in South America. Two oceanic plates converging form island arcs like the Philippine Islands.
Dangerous Volcanoes in Alaska
Aleutian arc
Alaska is home to more than 100 volcanoes along the 1,500 mile Aleutian Arc. The Aleutian Trench is the boundary between the Pacific Plate and the North American Plate. Major eruptions occur frequently along the Aleutian chain. Many times the islands are remote and only geologists know about the eruptions.
Air traffic dangers in Alaska
These eruptions pose a major threat to airline traffic that can inadvertently fly through an ash cloud causing their engines to shut down. Luckily there has not been a major airliner to crash because they flew through an ash cloud.
Pacific Northwest volcanoes
Cascade arc of volcanoes
The Cascade Arc in the Pacific Northwest is home to over 20 major volcanoes. There are over 4,000 volcanic vents in the area. The volcanic vents include stratovolcanoes, shield volcanoes, lava domes and cinder cones. The arc of volcanoes formed on the continental side of the Cascadia Subduction Zone stretches from British Columbia to Northern California.
Famous volcanoes in Pacific NW
Famous volcanoes in the Cascade Arc include Mount Saint Helens, Mount Rainier, Mount Hood and Mount Shasta.