Search results
Results from the WOW.Com Content Network
A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity ) lava , which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano .
This list of shield volcanoes includes active, dormant and extinct shield volcanoes. Shield volcanoes are one of the three types [ specify ] of volcanoes. They have a short cone shape, and have basaltic lava which means the lava has low viscosity (viscosity is a measure of the ability for a liquid to flow)
A shield is that part of the continental crust in which these usually Precambrian basement rocks crop out extensively at the surface. Shields can be very complex: they consist of vast areas of granitic or granodioritic gneisses , usually of tonalitic composition, and they also contain belts of sedimentary rocks, often surrounded by low-grade ...
[74] [26] The central shield volcano is the oldest, built mostly from 22 to 18 Ma but with a later phase from 17.5 to 13 Ma. The southern shield volcano formed from 21 to 14 Ma. The northern shield volcano was built mainly from 17 to 12 Ma. [75] These shield volcanoes erupted mostly basaltic and trachybasaltic lava flows. [26]
[1] [3] On shield volcanoes forming from level seafloor without neighboring vents, flank rifting occurs more evenly distributed around the vent. [1] However, where the flanks of a volcano may be supported on one side by the presence of a pre-existing feature, or burdened with various planes of weakness, rift zone formation promulgates according ...
Emi Koussi seen from International Space Station. In volcanology, a pyroclastic shield or ignimbrite shield is an uncommon type of shield volcano.Unlike most shield volcanoes, pyroclastic shields are formed mostly of pyroclastic and highly explosive eruptions rather than relatively fluid basaltic lava issuing from vents or fissures on the surface of the volcano. [1]
Volcanoes known to have subglacial activity include: Mauna Kea in tropical Hawaii. There is evidence of past subglacial eruptive activity on the volcano in the form of a subglacial deposit on its summit. The eruptions originated about 10,000 years ago, during the last ice age, when the summit of Mauna Kea was covered in ice. [60]
An example is the massive Level Mountain shield volcano in northern British Columbia, Canada, which covers an area of 1,800 km 2 (690 sq mi) and a volume of 860 km 3 (210 cu mi). [ 1 ] Perhaps the most extensive of all the subaerial basaltic plateaus existed during the Paleogene [ 2 ] and possibly extended over 1,800,000 km 2 (690,000 sq mi) of ...