Although the country's volcanic activity dates back to the Precambrian period, volcanic activity continues to occur in Western and Northern Canada where it forms part of an encircling chain of volcanoes and frequent earthquakes around the Pacific Ocean called the Pacific Ring of Fire. However, because volcanoes in Western and Northern Canada are in remote rugged areas and the level of volcanic activity is less frequent than with other volcanoes around the Pacific Ocean, Canada is commonly thought to occupy a gap in the Pacific Ring of Fire between the volcanoes of western United States to the south and the Aleutian volcanoes of Alaska to the north. However, the mountainous landscape of Western and Northern Canada includes more than 100 volcanoes that have been active during the past two million years and have claimed many lives. Volcanic activity has been responsible for many of Canada's geological and geographical features and mineralization, including the nucleus of North America called the Canadian Shield.
Volcanism has led to the formation of hundreds of volcanic areas and extensive lava formations across Canada, indicating volcanism played a major role in shaping its surface. The country's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ranging from passive lava eruptions to violent explosive eruptions. Canada has a rich record of very large volumes of magmatic rock called large igneous provinces. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions. The most capable large igneous provinces in Canada are Archean (3,800-2,500 million years ago) age greenstone belts containing a rare volcanic rock called komatiite.
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank that is 3,160 metres (10,370 ft) high may be the highest volcano in Canada. The main glaciers in the Silverthrone area are the Pashleth, Kingcome, Trudel, Klinaklini and Silverthrone glaciers. Most of the caldera lies in the Ha-Iltzuk Icefield, which is the largest icefield in the southern half of the Coast Mountains; it is one of the five icefields in southwestern British Columbia that thinned between the mid-1980s and 1999 due to global warming. Nearly half of the icefield is drained by the Klinakini Glacier, which feeds the Klinaklini River. The Silverthrone Caldera is very remote and rarely visited or studied by geoscientists, such as volcanologists. It can be reached by helicopter or—with major difficulty—by hiking along one of the several river valleys extending from the British Columbia Coast or from the Interior Plateau.
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17 February 2011: Earthquake activity occurs at Mount St. Helens, USA. The earthquake swarms occurred in the same area as those preceding St. Helen's famous 1980 eruption. No actions have yet taken place.