What type of volcanoes have high viscosity?
These rocks form Stratovolcanoes (also called composite volcanoes), due to the higher amounts of trapped gasses and the higher viscosity.
Do shield volcanoes have high or low viscosity?
Most commonly, they are comprised of basaltic lavas, but some shield lavas of the high silica 'peralkaline' family have very low viscosity – equivalent to or sometimes even lower than basalt (Figure 20). Figure 20. Shield volcanoes form over great spans of time with the effusion of low-viscosity lava.
What type of lavas make up most of shield volcanoes?
basalt Magma Composition Shield volcanoes are usually basalt but can be constructed of mostly andesitic lava flows. Mauna Loa and Kīlauea erupt almost exclusively basaltic lavas. Shield volcanoes in Wrangell-St. Elias National Park, are made up of andesitic lava flows.
What is a high viscosity volcano?
When lava has a high viscosity, it's very thick and doesn't flow very well at all. Instead of rivers of lava, you can get crumbling piles of rock flowing down hill. It can also clog up the volcanic vent and form blocks that resist the flow of lava.
What is an example of high viscosity?
Liquids which flow very slowly, like glycerin or honey, have high viscosities. Those like ether or gasoline which flow very readily have low viscosities. Viscosity is governed by the strength of intermolecular forces and especially by the shapes of the molecules of a liquid.
What type of volcano has the least violent eruption?
Strombolian and Hawaiian eruptions These are the least violent types of explosive eruptions.
Does a shield volcano erupt violently?
Eruptions at shield volcanoes are only explosive if water somehow gets into the vent, otherwise they are characterized by low-explosivity fountaining that forms cinder cones and spatter cones at the vent, however, 90% of the volcano is lava rather than pyroclastic material.
What type of volcano has low viscosity?
shield volcano Where a volcano produces low viscosity, runny lava, it spreads far from the source and forms a volcano with gentle slopes: a shield volcano. Most shield volcanoes are formed from fluid, basaltic lava flows. Mauna Kea and Mauna Loa are shield volcanoes.
Do shield volcanoes erupt violently?
Eruptions at shield volcanoes are only explosive if water somehow gets into the vent, otherwise they are characterized by low-explosivity fountaining that forms cinder cones and spatter cones at the vent, however, 90% of the volcano is lava rather than pyroclastic material.
Which type of volcano has gentle slopes?
Shield volcanoes Where a volcano produces low viscosity, runny lava, it spreads far from the source and forms a volcano with gentle slopes: a shield volcano. Most shield volcanoes are formed from fluid, basaltic lava flows.
Do less viscous lavas explode more easily than highly viscous lavas?
Highly viscous magma holds gas more easily than does less viscous lava. Viscous magma in important in determinging how explosive an eruption will be. Viscosity of magma increases as the temperature decreases.
What does high and low viscosity mean?
Viscosity is a measure of a fluid's resistance to flow. A fluidwith large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion.
Is high viscosity fast or slow?
A fluid that is highly viscous has a high resistance (like having more friction) and flows slower than a low-viscosity fluid. To think of viscosity in everyday terms, the easier a fluid moves, the lower the viscosity.
What type of volcanoes are formed from viscous or sticky lava that does not flow easily?
Stratovolcano. Stratovolcanoes have relatively steep sides and are more cone-shaped than shield volcanoes. They are formed from viscous, sticky lava that does not flow easily.
Which type of volcano has the most violent eruptions?
Stratovolcanoes Stratovolcanoes are considered the most violent. Mount St. Helens, in Washington state, is a stratovolcano that erupted on May 18, 1980.
How does a shield volcano erupt?
Eruptions at shield volcanoes are only explosive if water somehow gets into the vent, otherwise they are characterized by low-explosivity fountaining that forms cinder cones and spatter cones at the vent, however, 90% of the volcano is lava rather than pyroclastic material.
What type of volcano has a gentle eruption?
Shield volcanoes Shield volcanoes: gentle slopes; runny lava; lava flows quickly; lava may flow far; erupt less violently.
How do shield volcanoes erupt?
Eruptions at shield volcanoes are only explosive if water somehow gets into the vent, otherwise they are characterized by low-explosivity fountaining that forms cinder cones and spatter cones at the vent, however, 90% of the volcano is lava rather than pyroclastic material.
What causes shield volcanoes to erupt?
They are zones of weakness within a volcano that magma can easily move into. This causes frequent eruptions along these zones that continue to widen over time because of magma flowing into them. Dike complexes (the subsurface manifestation of eruptive fissures) often underlie the caldera and rift zones.
How do shield volcanoes form?
A shield volcano is built mainly out of basaltic lava of low viscosity. The lava flows out, cools and hardens, adding to layers of cooled and hardened lava underneath it. This process creates a gradual increase in elevation over time resulting in the formation of shield volcanoes.
What does shield volcano mean?
Definition of shield volcano : a broad rounded volcano that is built up by successive outpourings of very fluid lava — see volcano illustration.
How does viscosity affect volcanic eruptions?
The viscosity of the magma, however, is also an important factor in determining whether an eruption will be explosive or nonexplosive. A low-viscosity magma, like basalt, will allow the escaping gases to migrate rapidly through the magma and escape to the surface.
What is the difference between high and low viscosity magma?
High viscosity lavas flow slowly and typically cover small areas. In contrast, low viscosity magmas flow more rapidly and form lava flows that cover thousands of square kilometers.
What has a high viscosity?
Some liquids, like pitch, glass and peanut butter, have such high viscosity they behave like solids. In common vernacular, a liquid is said to be “viscous” if its viscosity is substantially greater than that of water, and is described as “mobile” if the viscosity is noticeably less than water.
What causes high viscosity?
Hyperviscosity can be caused by your blood cells changing shape or by an increase in serum proteins, red blood cells, white blood cells, or platelets. The reduced blood flow caused by hyperviscosity syndrome is a dangerous phenomenon and can have far-reaching effects on the whole body.
Which type of volcano has gentle slopes and forms at a divergent plate boundary?
Shield Volcanoes. Most shield volcanoes are associated with mantle plumes, although some form at divergent boundaries, either on land or on the sea floor. Because of their non-viscous mafic magma they tend to have relatively gentle slopes (2 to 10˚) and the larger ones can be over 100 km in diameter.
What type of volcano lava can flow gently and violently?
Shield volcanoes Shield volcanoes: gentle slopes; runny lava; lava flows quickly; lava may flow far; erupt less violently.
Are shield volcanoes explosive?
Eruptions at shield volcanoes are only explosive if water somehow gets into the vent, otherwise they are characterized by low-explosivity fountaining that forms cinder cones and spatter cones at the vent, however, 90% of the volcano is lava rather than pyroclastic material.
How are shield volcanoes formed?
A shield volcano is built mainly out of basaltic lava of low viscosity. The lava flows out, cools and hardens, adding to layers of cooled and hardened lava underneath it. This process creates a gradual increase in elevation over time resulting in the formation of shield volcanoes.
What is the slope of shield volcanoes?
A shield volcano is characterized by gentle upper slopes (about 5o) and somewhat steeper lower slopes (about 10o).