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The Canada and Western USA Region
This region was originally restricted to the United States by the organizers of the CAVW, but we added Canada (as subregion 1200) in our first edition. If we add the US volcanoes here (subregions 1201-1210) to those of Alaska and Hawaii, we find 52 historically active volcanoes, tying the US for third with Russia (behind Indonesia with 78 and Japan with 66) in this national ranking. If volcanoes in the Commonwealth of the Northern Marianas Islands and American Samoa, and the North Gorda Ridge volcanic segment about 200 km off the coast of Oregon are included, the number of US historically active volcanoes rises to 64, approaching Japan's total of 66.
Volcanoes of region 12 occupy tectonic environments ranging from the subduction volcanism that dominates the Cascade Range to the extensional tectonics controlling vast regions of the western interior, giving region 12 the largest number (and percent) of volcanoes consisting primarily of cinder cone fields. Only Mount St. Helens and Lassen volcanoes in this region have had unequivocal eruptions in the past century, although eruptions have occurred since 1800 AD at glacier-clad Baker, Rainier, and Hood volcanoes in the Cascade Range, and radiocarbon dates document eruptions in the 18th-19th centuries from the Tseax River and Iskut-Unuk River cinder cones in British Columbia. Native American legends describe eruptions of Sunset Crater, Arizona, for many years dated to 1064-65 AD by tree-ring counts, but this precise date is now considered unreliable, and the eruption has been dated by paleomagnetism to the 2nd half of the 11th century. After the historic voyages of Columbus, Spain dominated exploration of North America in the 16th century, with the Grand Canyon first viewed by western eyes in 1540 and the Oregon coast only 4 years later. Permanent inland settlement of Santa Fe came in 1609, only 2 years after the first settlement on the east coast by the British. The founding of the Massachusetts Bay Colony in 1630 started the great emigration to eastern North America. Exploration of the west was slow, though, and it was not until the 1770s that Captain Cook closed the gap between Spaniards working north along the coast and Russians moving toward them from the far northwest. Cook brought publicity to the Pacific coast, and by the end of the century ships from 6 nations were busily trading furs along seacoasts that 20 years earlier had not been seen by Europeans. The first documented eruption in the region was California's Shasta, in 1786. By that year every other region in the world, except Antarctica, had documented at least one historical eruption, and over half of region 01's current list of historical volcanism had been recorded. In the latter half of the 18th century, while the US was gaining independence in the east, the Rocky Mountains were being explored by the British and French. In 1805 Lewis and Clark sighted the Pacific, and the first historical eruptions of Mount St. Helens were witnessed by settlers in the 1830s. In 1841 the first wagon train reached the Oregon Territories, and in 1848 gold was discovered in California. It was not until the end of the Civil War, though, that westward emigration exploded: the first transcontinental railroad was completed in 1869, and by 1890 the US Census Bureau Director declared that the American frontier was at an end. The US Geological Survey was founded in 1879 and from 1926 through 1931 operated a volcano observatory at Lassen, following that volcano's 1914-17 eruption. The second confirmed Cascade eruption of the century, at Mount St. Helens, brought the founding of the Cascades Volcano Observatory in 1980, and observatories followed documenting volcanic unrest at the major silicic calderas of Long Valley and Yellowstone.
List of Holocene volcanoes in the Canada and Western USA region.