Shield volcanoes:
so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent, but not generally explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The hawaiian volcanic chain is a series of shield cones.Mount haleakala, mount kilauea and mount mauna loa are example of active shield volcanoes on hawaii
Next the cinder cone volcanoes:
This lovely cinder cone is Pu'u ka Pele, sitting on the flank of Mauna Kea volcano, Hawaii.
A cinder cone is a volcanic cone built almost entirely of loose volcanic fragments called cinders . They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone. Most cinder cones have a bowl-shaped crater at the summit.
from ;http://en.wikipedia.org/wiki/Volcanic_cone
next is the composite volcanoes:
Composite volcanoes is a tall, conical, volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruption. The lava that flows from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica(as in rhyolite, dacite, or andesite, with lesser amounts of less-viscous mafic magma.
information form:http://en.wikipedia.org/wiki/Composite_Volcanoes
No comments:
Post a Comment