Silverthrone Caldera

The Silverthrone Caldera, also referred to as the Silverthrone Caldera Complex, is a volcano in Range 2 Coast Land District of British Columbia, Canada. It lies within the Pacific Ranges of the Coast Mountains and reaches an elevation of 2,860 metres (9,380 feet), although some sources give the elevation as high as 3,160 m (10,370 ft). The caldera is about 25 by 20 kilometres (16 by 12 miles) in size and has been deeply eroded, resulting in the formation of rugged topography. Several glacial meltwater streams originating from the volcano flow through valleys in the Pacific Ranges. These include the Pashleth, Selman and Catto creeks and the Kingcome and Wakeman rivers. The caldera contains several named mountains, including Mounts Somolenko, Overill, Kinch, Squire, Ardern and Calli, as well as Petrovsky Peak and Silverthrone Mountain.

Volcanic rocks deposited by eruptions of the Silverthrone Caldera and associated vents include rhyolites, dacites, andesites and basaltic andesites. They are exposed in valleys, but at higher elevations they are largely buried under glacial ice of the 3,600 km2 (1,400 mi2) Ha-Iltzuk Icefield. These rocks comprise three geological units: a 750,000-year-old basal breccia unit, a 400,000-year-old unit of overlying lava flows and domes, and a less than 13,000-year-old series of lava flows and pyroclastic cones. Small magnitude, shallow earthquakes have been recorded near the volcano since 1980, but they have not been demonstrated to be magmatic in origin.