VOLCANOES

BY MUNEEBA FATIMAMSc-ZOW,UoK

WHAT IS VOLCANO ?A volcano is a vent or 'chimney' that

connects molten rock (magma) from within the Earth’s crust to the Earth's surface.

The volcano includes the surrounding cone of erupted material.

Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.

How are volcanoes formed?

Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.

What are the different stages of volcanoes?

Scientists have categorized volcanoes into three main categories: active, dormant, and extinct. An active volcano is one which has recently erupted and there is a possibility that it may erupt soon. A dormant volcano is one which has not erupted in a long time but there is a possibility it can erupt in the future. An extinct volcano is one which has erupted thousands of years ago and there’s no possibility of eruption.

MAGMA - Magma is the liquid rock inside a volcano.

LAVA - Lava is the liquid rock (magma) that flows out of a volcano. Lava glows red hot to white hot as it flows.

ACTIVE VOLCANO - An active volcano is one that erupts regularly.

DORMANT VOLCANO - A dormant volcano is one that has not erupted for many years, although there is still some activity deep inside.

EXTINCT VOLCANO - An extinct volcano is a volcano that is no longer active.

GEYSERS - Geysers are springs that throw boiling water high in the air. They are caused by volcanic heat warming trapped ground water.

ASH - Ash are very small fragments of lava or rock blasted into the air by volcanic explosions.

PUMICE - It is a light-colored volcanic rock containing lots of bubbles from trapped gases.

Why do volcanoes erupt?

The Earth's crust is made up of huge slabs called plates, which fit together like a jigsaw puzzle. These plates sometimes move. The friction causes earthquakes and volcanic eruptions near the edges of the plates. The theory that explains this process is called plate tectonics.

What are plate tectonics?

The theory of plate tectonics is a interesting story of continents drifting from place to place breaking apart, colliding, and grinding against each other. The plate tectonic theory is supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. The plates are all moving in different directions and at different speeds. Sometimes the plates crash together, pull apart or sideswipe each other. When this happens, it commonly results in earthquakes.

What is the difference between lava and magma

Magma is liquid rock inside a volcano. Lava is liquid rock (magma) that flows out of a volcano. Fresh lava glows red hot to white hot as it flows.

Hot, molten rock (magma) is buoyant (has a lower density than the surrounding rocks) and will rise up through the crust to erupt on the surface. Same principle as hot air rising, e.g. how a hot air balloon works

When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts.

Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption! Think about shaking a carbonated drink and then releasing the cap.

Small amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption Where the magma just trickles out of the volcano (lava flow).

How and why do volcanoes erupt?

Three products from an explosive eruptionAsh fallPyroclastic flowPyroclastic surge

Explosive Eruptions

Pyroclastic flows on Montserrat, buried the capital city.

A pyroclastic surge is a fluidized mass of turbulent gas and rock fragments which is ejected during some volcanic eruptions

A pyroclastic flow (also known scientifically as a pyroclastic density current) is a fast-moving current of hot gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph). The gas can reach temperatures of about 1,000 °C (1,830 °F).

Explosive EruptionsExplosive volcanic

eruptions can be catastrophic

Erupt 10’s-1000’s km3 of magma

Send ash clouds >25 km into the stratosphere

Have severe environmental and climatic effects

Hazardous!!!

Above: Large eruption column and ash cloud from an explosive eruption at Mt Redoubt, Alaska

The volcano is about the size of the state of New Mexico and is among the largest in the solar system, Sager says. Tamu Massif covers an area of about 120,000 square miles. In comparison, the largest active volcano on land, Hawaii's Mauna Loa, is about 2,000 square miles, Sager says.Sep 7, 2013

Nguna Extinct Volcano Near Utanlangi Village

Dominant volcano

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