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.

Does lava have high viscosity?

Even though lava is 100,000 times more viscous than water, it can still flow great distances. When lava has low viscosity, it can flow very easily over long distances. ... But most importantly, highly viscous lava is associated with explosive eruptions and dangerous pyroclastic flows.

Do shield volcanoes have high or low viscosity?

Shield volcanoes are formed by lava flows of low viscosity - lava that flows easily. Consequently, a volcanic mountain having a broad profile is built up over time by flow after flow of relatively fluid basaltic lava issuing from vents or fissures on the surface of the volcano.

What type of magma has the lowest silica content?

Basaltic magma is mafic, has a low viscosity, a high temperature, and a low silica content.

Why does basaltic magma have the lowest viscosity quizlet?

LOW-SILICA mafic magma flow readily and have a LOW VISCOSITY. ... LOW-SILICA content, BASALTIC lava flow may have a LOW VISCOSITY when it erupts onto earth's surface, but as it flows down the flank of the volcano and cools, its VISCOSITY will increase, causing the flow to move more slowly and change in form.

Which type of magma has the highest silica content and viscosity?

Felsic magma has the highest silica content of all magma types, between 65-70%. Thick, viscous felsic magma can trap gas bubbles in a volcano's magma chamber.

Which type of magma lava has the lowest viscosity and least violent eruptions?

Non explosive eruptions are favored by low gas content and low viscosity magmas (basaltic to andesitic magmas).

Is felsic magma viscous?

Felsic lavas are not as hot, high in silica and volatiles, and have a high viscosity. They are thick and gooey and resist flowing.

Why are lava domes viscous?

This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite.

Which of the following does not affect viscosity of magma?

Question: Which of the following does not affect the viscosity of magma? Temperature Silica Content Amount of gas None of these affects the viscosity of the magma.

Which volcano is the least explosive?

Shield volcanoes tend to be the least explosive volcanoes. Most of the material they produce is lava, rather than the more explosive pyroclastic material.

What are 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 is basaltic magma?

Basaltic lava, or mafic lava, is molten rock enriched in iron and magnesium and depleted in silica. Basaltic magmas are formed by exceeding the melting point of the mantle either by adding heat, changing its composition, or decreasing its pressure. ... Underwater, basaltic lavas are erupted as pillow basalts.

What type of magma has a low viscosity low silica content and is created at divergent plate boundaries?

Shield volcanoes are found on divergent plate boundaries , where two plates move away from one another. Shield volcanoes have the following characteristics: Basaltic magma, which is high in temperature, very low on silica and with low gas content.

Why is rhyolitic magma highest viscosity?

Magma Composition:

Such magmas erupt as andesites and rhyolites or are intruded as granite masses. The more extensive silicate chain molecules render these magmas highly viscous, so when eruption occurs it is usually explosive (e.g. Mt St Helens).

Is basaltic lava thick or thin?

They are relatively thin (1-2 m) and very fluid with low viscosities. They advance downslope in a sort of smooth "rolling motion." The front of the flow usually advances as a thin (< 20 cm) glowing lobe that will chill and crust over after 1-2 meters of flow.

Which magma composition causes the most violent volcanic eruptions quizlet?

A more viscous (thick) magma will produce a more violent eruption This is controlled in part by the concentration of silica in the magma. A magma with low silica (<45%) will be runny and so the eruption will not be explosive. A magma with high silica (>60%) will be quite viscous and so the eruption will be violent.

Which magma has the most silica?

Rhyolitic magma contains the most silica. Silica is a chemical compound with the formula SiO2. Rhyolitic magma contains approximately 65 to 75...