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The Mount Edziza volcanic complex is a linear group of volcanoes in northwestern British Columbia, Canada. [8] [9] It is about 65 kilometres (40 miles) long and 20 kilometres (12 miles) wide, consisting of several stratovolcanoes, shield volcanoes, subglacial volcanoes, lava domes and cinder cones.
The collapse may have been caused by a violent, climactic eruption, effusion of the Kakiddi lava flows or the outpouring of voluminous lava during dome formation. [25] Prior to collapse, the summit of Mount Edziza was at least 610 metres (2,000 feet) higher than its current elevation of 2,786 metres (9,140 feet). [5] [26]
Dacite and rhyolite lavas are normally too viscous to flow away from a volcanic vent, resulting in the formation of lava domes. [25] An exception is the 15-kilometre-long (9.3-mile) Ring Creek dacite lava flow from Opal Cone on the southeastern flank of Mount Garibaldi, a length that is normally attained by basaltic lava flows. [19]
The Big Raven Plateau is volcanic in origin, consisting mostly of basaltic lava flows of the Mount Edziza volcanic complex that were erupted in the last 7.5 million years. These lava flows are interbedded with rhyolite and trachyte which are in the form of rock fragments produced and ejected by explosive eruptions.
More than 100 eruptions have occurred in the past 20 million years with a broad range of eruptive styles. [2] These volcanic processes have created a range of different volcanic landforms, including stratovolcanoes, [4] shield volcanoes, [5] lava domes [6] and cinder cones, [7] along with a few isolated examples of rarer volcanic forms such as tuyas. [8]
Andesite from the Lava Divide era, the first and longest eruptive period which spanned 460,000 to 296,000 years ago, probably produced a large volcanic cone, but it has now been reduced to a ridge. Lava flows made of andesite from 455,000 to 366,000 years ago were generated from a vent now buried under Mount Baker; at least two have ...
As a result of this fluidity, the peralkaline felsic lava flows were able to form small-scale folds and 1-to-2-metre-diameter (3.3-to-6.6-foot) lava tubes. The liquidus temperatures of these flows were in excess of 1,200 degrees Celsius (2,190 degrees Fahrenheit) with viscosities as low as 100,000 poise .
The word lava comes from Italian and is probably derived from the Latin word labes, which means a fall or slide. [2] [3] An early use of the word in connection with extrusion of magma from below the surface is found in a short account of the 1737 eruption of Vesuvius, written by Francesco Serao, who described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of ...