| Question Answer | When you talk about the viscosity of lava, you are talking about how the lava _______. flows | Cool, stiff lava that forms jumbled heaps of sharp chunks near the vent aa lava | The pyroclastic material that can reach the upper atmosphere and circle the Earth for years volcanic ash |
|---|
What is the viscosity of lava?
With such a high silica content, these lavas are extremely viscous, ranging from
10
8
cP for hot rhyolite lava at 1,200 °C
(2,190 °F) to 10
11
cP for cool rhyolite lava at 800 °C (1,470 °F). For comparison, water has a viscosity of about 1 cP.
What does viscosity mean in terms of magma lava?
Viscosity of Magmas
Viscosity is
the resistance to flow (opposite of fluidity)
. Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO
2
(silica) content magmas have higher viscosity than lower SiO
2
content magmas (viscosity increases with increasing SiO
2
concentration in the magma).
What is the viscosity of lava determined by?
A magma’s viscosity is largely controlled by
its temperature, composition, and gas content
(see downloadable programs at the bottom of this page). The effect of temperature on viscosity is intuitive. Like most liquids, the higher the temperature, the more fluid a substance becomes, thus lowering its viscosity.
What does viscous lava form?
Viscous lava will
trap pockets of gas within the rock
, and not let them pop as bubbles on the surface. But most importantly, highly viscous lava is associated with explosive eruptions and dangerous pyroclastic flows. An example of a low viscosity (fast flowing) lava is basaltic lava.
Is lava hotter than fire?
While lava can be as hot as 2200 F, some flames can be much hotter, such as 3600 F or more, while a candle flame can be as low as 1800 F.
Lava is hotter than a typical wood
or coal-buring fire, but some flames, such as that of an acetylene torch, is hotter than lava.
Which lava has the highest viscosity?
The magma that has the highest viscosity is
rhyolitic magma
.
What type of volcano has low viscosity?
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. Mauna Kea and Mauna Loa are shield volcanoes.
How does viscosity affect the shape of volcanoes?
Magma and a Volcanoes Shape
Differences
in a magma’s viscosity
will determine the shape a volcano takes. High-silica (basalt) magma has a much lower viscosity. It flows much easier and over longer distances. As low-silica magma cools, it hardens to rock, adding a new thin layer of rock to the volcano.
What is highly viscous?
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. … Honey would move slower than water, so honey would have a greater viscosity.
What are 3 types of magma?
There are three basic types of magma:
basaltic, andesitic, and rhyolitic
, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium.
What are the 3 types of lava flow?
The most common way to divide lava flows into distinct types is following:
Pahoehoe lava flow, Aa lava flow, Blocky lava flow, and also Pillow lava flow
.
What is an example of high viscosity?
The resistance to such flow is called the viscosity.
Liquids which flow very slowly, like glycerin or honey
, have high viscosities. … Honey, mostly glucose and fructose (see image below) is a good example of a liquid which owes its viscosity to hydrogen bonding.
Why is viscous magma more explosive?
High volatile contents (gas and water) make magma less viscous but when they escape during eruption, the lava becomes more viscous, which
allows the bubbles to build up pressure
and which eventually will tear the highly viscous magma apart and make a big explosion.
Which type of volcanoes is the most explosive?
Stratovolcanoes
are considered the most violent. Mount St. Helens, in Washington state, is a stratovolcano that erupted on May 18, 1980.
Which component of magma is the highest and lowest in value?
Felsic magma
has the highest silica content of all magma types, between 65-70%. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650
o
and 800
o
Celsius (1202
o
and 1472
o
Fahrenheit).
