Volcanic Eruptions

Describe pyroclastic materials and lava.

What is pyroclastic material?

Pyroclastic material consists of fragments of rock that form during volcanic eruption.

Pyroclastic Material

Some pyroclastic materials form when magma breaks into fragments during an eruption. Other form when fragments of erupting lava cool and solidify. Scientist classify pyroclastic materials according to their sizes.

Pyroclastic particles that are less than 2mm in diameter are volcanic ash. Volcanic ash that is less than 0.25mm in diameters is called volcanic dust. Large pyroclastic particles that are less than 64mm in diameter are called lapilii. Large clots of lava may be thrown out of an rut piling volcano. As they spin through the air they cool and develops round or single shape. These pyroclastic materials are called volcanic bombs. The largest pyroclastic materials are known as blocks they form from solid rock that is blasted from the vent. Felsic lava tends to explode and throw Pyroclastic material into the air.. Felsic lavas of continental volcanoes, such as Mount St. Helens, tend to be more cooler and stickier. Felsic lava is contains Silica and Feldspar. Felsic lava contain large amounts of trapped gases, such as water vapor and carbon dioxide. When a volcano erupts the gases within the lava escape and send molten and solid particles into the air. It throws pyroclastic materials into the air. It also is light-colored and has a a high viscosity.

Pyroclastic material are classified according to the size of the particles

Types Of Lava

Types of lava

There are three different types of Mafic lava; Pahoehoe,Aa, and Blocky lava.

Mafic magma has a low viscosity meaning the lava moves much slower. It contains magnesium and Iron. It has less trapped gases and is dark in color. Mafic lava causes quiet eruptions.

Three Types Of Volcanoes

There are three different Types of Volcanoes.

Shield Volcanoes,Cinder Cones, and Composite Volcanoes.

Shield Volcanoes are broad at the base and have gently sloping sides. It covers a wide area and generally forms quiet eruptions. Layers of hot,Mafic lava flows out around the vent and hardens.Cinder Cones has very steep slopes. The slope angles of the cinder cones can be 40,and are rarely more than a 100 meters high. Cinder ones form from explosive eruptions and are made of pyroclastic material. Composite Volcanoes are made of alternating layers of hardened lava flows and pyroclastic material. Composite volcanoes have both quiet and explosive eruptions.

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