Mafic magma
has less silica content and more iron and magnesium in it. The amount of gas in the magma helps determine how explosive the eruption will be.
What lava is low in silica?
So,
mafic lavas
are hot , low in silica and volatiles, and have relatively low viscosity. They flow easily outward from the vent (where it comes out of the ground), and may travel great distances before completely solidifying. Felsic lavas are not as hot, high in silica and volatiles, and have a high viscosity.
Which type of lava has the lowest silica content?
Because
basalt
contains the least amount of silica and erupts at the highest temperature compared to the other types of lava, it has the lowest viscosity (the least resistance to flow). Thus, basalt lava moves over the ground easily, even down gentle slopes.
What type of volcano has low silica content?
1)
Shield Volcano
: low silica content produces a fluid lava that flows out of a vent and builds up layer upon layer producing a “classic” volcanic cone shape. Shield cones are very tall with a broad base.
What is low silica magma?
Magma with low silica content is
very fluid and easily erupts onto the surface through cracks and crevices at
the surface. Over time the layers of lava build up a volcanic cone. Low silica volcanoes are characterized by “quiet” eruptions. Lava is able to easily flow out of the ground.
What is the weakest volcano?
| VEI | 0 | Plume height | <100 m (330 ft) | Eruptive volume * | 1,000 m 3 (35,300 cu ft) | Eruption type | Hawaiian | Example | Kilauea |
|---|
Which magma has the highest silica?
| SiO2 CONTENT MAGMA TYPE VOLCANIC ROCK | ~50% Mafic Basalt | ~60% Intermediate Andesite | ~65% Felsic (low Si) Dacite | ~70% Felsic (high Si) Rhyolite |
|---|
Is there silica in lava?
Felsic or silicic lavas have a
silica content greater than 63%
. They include rhyolite and dacite lavas. 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).
What’s a dead volcano called?
A dormant volcano is one that is “sleeping” but could awaken in the future, such as Mount Rainier and Mount Fuji.
An extinct volcano
is “dead” — it hasn’t erupted in the past 10,000 years and is not expected to ever erupt again.
What is the largest volcano?
Mauna Loa on the Island Hawaiʻi
is the world’s largest volcano. People residing on its flanks face many hazards that come with living on or near an active volcano, including lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and local tsunami (giant seawaves).
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.
Do composite volcanoes have high silica?
Composite volcanoes have the following characteristics: Andesitic magma, which is lower in temperature,
has more silica
and a lot of dissolved gases and is more likely to explode when it reaches the surface. Acidic lava, which is very viscous (sticky). Steep sides as the lava doesn’t flow very far before it solidifies.
Which magma type flows the fastest?
PAHOEHOE
– has a shiny, smooth, glassy surface. It tends to be more fluid (lower viscosity), hence flows more quickly and produces thinner flows (typically 1-3 m).
What is low silica content?
The low levels of silica mean that
Hawaiian magma has a low viscosity
, which explains why we see lava readily cascading downslope, and being churned up in the air in great fire fountains. At the other end of the spectrum we have magma that is formed from ‘felsic’ volcanic rock, which has a much higher silicon content.
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.
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).
