How can you tell if a volcano makes felsic or basaltic lava?

Temperature: The hotter the lava, the lower the viscosity (the thinner it is). The cooler the lava, the higher the viscosity (the thicker it is). Composition: he more felsic the lava (the more silica in the lava), the higher the viscosity because silica forms chains in the cooling lava even before it crystallizes.

Do all volcanic eruptions look the same?

No, the same volcano can produce different magmas at different times and sometimes even in the same eruption. It depends on what has melted to form the magma in the magma chamber and what this magma has mixed with on its way to the surface.

What are the two types of eruptions we can see from a volcano and how are they different?

There are two types of eruptions in terms of activity, explosive eruptions and effusive eruptions. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra. Effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption.

What does a quiet volcanic eruption look like?

Technically speaking, “quiet” eruptions are known as effusive eruptions. These relatively tame eruptions are characterized by an outpouring of thin, liquid-like lava, as seen with many Hawaiian volcanoes.

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.

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).

What type of volcano has the least violent eruption?

Shield volcanoes are built by many layers over time and the layers are usually of very similar composition. The low viscosity also means that shield eruptions are non-explosive. Eruptions tend to be mild in comparison to other volcanoes, but lava flows can destroy property and vegetation.

How do different types of volcanoes vary in eruption?

Types of eruptions. The style of eruption depends on a number of factors, including the magma chemistry and content, temperature, viscosity (how runny the magma is), volume and how much water and gas is in it, the presence of groundwater, and the plumbing of the volcano.

What kind of volcanic eruption is least explosive?

Shield volcanoes
Shield volcanoes tend to be the least explosive volcanoes.

Which volcano is the least explosive?

The least explosive type of volcano is called a basalt plateau. These volcanoes produce a very fluid basaltic magma with horizontal flows. The form of these volcanoes is flat to gently sloping and they can occupy an area from 100,000 to 1,000,000 square kilometers.

What is a silent volcano?

Dormant: An active volcano which is quiet, not presently erupting, but is expected to erupt in the future. Eruption: The expelling of material including gases, ash, volcanic fragments and lava on Earth’s surface due to volcanic activity. Eruptions may be explosive, or quiet lava flows.

Why are some volcanic eruptions quiet?

When a volcano has magma that is hot or low in silica a quiet eruption occurs. The magma that causes quiet eruptions is low in viscosity and is is classified as mafic magma. The mafic magma is rich in magnesium and iron, which causes its dark color. A short, violent, relatively small explosion of viscous magma.

What are the characteristics of volcanic eruption?

Volcanic Eruptions. Eruptions can be effusive, where lava flows like a thick, sticky liquid, or explosive, where fragmented lava explodes out of a vent. In explosive eruptions, the fragmented rock may be accompanied by ash and gases; in effusive eruptions, degassing is common but ash is usually not.

What is the magma that erupts from a volcano called?

Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. How explosive an eruption is depends on how runny or sticky the magma is. If magma is thin and runny, gases can escape easily from it. When this type of magma erupts, it flows out of the volcano.

What are some examples of volcanic eruptions that don’t kill people?

A good example is the eruptions at Hawaii’s volcanoes. Lava flows rarely kill people because they move slowly enough for people to get out of their way. If magma is thick and sticky, gases cannot escape easily. Pressure builds up until the gases escape violently and explode. A good example is the eruption of Washington’s Mount St. Helens.

What type of lava comes out of a volcano in Hawaii?

In a Hawaiian eruption, fluid lava is ejected from a vent as fire fountains or lava flows. The 1969 eruption at Mauna Ulu, a vent of Kilauea Volcano in Hawaii, was a spectacular example of fire fountaining.