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Because dacite is the main type of lava erupted from Mount Garibaldi, lava flows are a low to moderate hazard. [3] Dacite is felsic [ d ] in composition, containing 62–69% silica content. [ 71 ] [ 72 ] This high percentage in silica content increases the viscosity of dacitic melts relative to that of andesite or basalt , generally resulting ...
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]
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 .
Low viscosity lava can generate massive lava fountains, while lava of thicker viscosity can solidify within the vent, creating a volcanic plug. Volcanic plugs can trap volcanic gas and create pressure in the magma chamber, resulting in violent eruptions. [36] Lava is typically between 700 and 1,200 °C (1,300–2,200 °F). [37]
Karapınar Field in Turkey SP Crater in the San Francisco volcanic field is a cinder cone with a basalt lava flow that extends for 4 miles (6 km). El Muweilih Crater in Sudan with natron-rich clay on the crater floor
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 ...
Morphologically, these flows are reddish-black aa lava flows and feature blocks with sizes of 5 m. [34] The northern flow has prominent levee-like structures [41] and splits into a northwestern and northeastern branch [18] upon reaching an obstacle. [42] The southwestern [18] lava flow is 6 km long and was fairly viscous when it was erupted. [40]
The eruption of overlapping andesitic lava flows accumulated to build the volcano. By the time it reached its peak size, the volcano was immense, measuring at its base between 11 mi (18 km) and 15 mi (24 km) wide and more than 11,000 ft (3,353 m) tall. [ 7 ]