Cascade Volcanic Arc

chain of volcanoes in western North America

The Cascade Volcanic Arc (also known as the Cascade volcanoes or the Cascade Arc) is a major range of volcanoes in southwestern British Columbia, Washington, Oregon and in northern California. The arc is central to the Cascade Range, a mountain range in the Pacific Northwest. It includes about 20 major volcanoes, among a total of over 4,000 separate volcanic vents.[1]

Cascade Volcanic Arc.jpg
Major Cascade volcano eruptions in the last 4000 years

Twelve volcanoes in the arc are over 10,000 ft (3,000 m) in height, and the two highest, Mount Rainier and Mount Shasta, are over 14,000 ft (4,300 m). By volume, the two largest Cascade volcanoes are the broad shields of Medicine Lake Volcano and Newberry Volcano, which are about 145 mi³ (600 km³) and 108 mi³ (450 km³) respectively.

The volcanism in the arc began about 37 million years ago, but most of the present-day Cascade volcanoes are less than 2 million years old. The most recent major catastrophic eruption in the arc was at Mount St. Helens on May 18, 1980.

The major volcanoes within the arc include Mount Silverthrone, Mount Meager, Mount Cayley, Mount Garibaldi, Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, Mount Adams, Mount Hood, Mount Jefferson, Three Sisters, Broken Top, Mount Bachelor, Newberry Volcano, Mount Thielsen, Mount Mazama (Crater Lake), Mount McLoughlin, Medicine Lake Volcano, Mount Shasta, Shastina,Mount Tehama and Lassen Peak.


  1. Madson, J.K. et al 2006. Cenozoic to Recent plate configurations in the Pacific Basin: Ridge subduction and slab window magmatism in western North America. 42 (1). Geological Society of America. pp. 27, 28, 31.
  • Harris, Stephen L. 2005. Fire mountains of the West: the Cascade and Mono Lake volcanoes. 3rd ed, Mountain Press Publishing Company. ISBN 978-0-87842-220-3

Other websitesEdit