"volcano explanation"

Volcano Explanation

EXCHEL CORP

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VolcanoA volcano is a rupture on the crust of a planetary

mass object, such as the Earth, which allows hot lava,

volcanic ash, and gases to escape from a magma

chamber below the surface.

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Magma ChamberA magma chamber is a large underground pool of

liquid rock found beneath the surface of the Earth.

The molten rock in such a chamber is under great

pressure, and given enough time, that pressure can

gradually fracture the rock around it creating outlets

for the magma.

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LavaLava is the rock expelled from a volcano during an

eruption. When it first comes out, the lava can have a

temperature higher than 700 degrees C. It then flows

downhill from the eruption point until it cools and

hardens.

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Main VentA volcano’s main vent is the point in the Earth’s crust

where hot magma has reached the surface. The

familiar cone-shaped volcano builds up as ash, rock

and lava ejected during eruptions fall back to Earth

around the vent.

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CraterA volcanic crater is a circular depression in the ground

caused by volcanic activity. A volcano’s vents are

located at the bottom of the crater.

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Pyroclastic Flows Pyroclastic flows are fast moving currents of hot gas

and rock with travel down hill from a volcano,

reaching speeds of 700 km/hour. The gas can reach

temperatures of more than 1,000 degrees C, and is

one of the greatest dangers from volcanic eruptions.

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Ash Cloud Volcanic ash consists of small pieces of pulverized

rock and glass created during volcanic eruptions.

These fragments are so small, and heated to such a

temperature that they can be carried in the air for

many kilometers.

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Volcanic BombsVolcanic bombs are chunks of lava blasted into the

air which solidify before they reach the ground. Some

bombs can be extremely large, measuring 5-6 meters

in diameter and landing more than 500 meters from

the volcanic vent.

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Negative Effects of Volcanoes• Eruptions occurring close to human settlements may

spill and destroy lives and property. People often

have to be evacuated.

• Landscapes and natural sceneries can be

destroyed.

• Ash and mud can mix with rain and melting snow,

forming lahars. Lahars are mudflows flowing at very

fast pace.

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The negative effects of volcanoes eruption J

Positive Effects of Volcanoes• Different types of erupting volcanoes provide

extraordinary scenery, so beautiful and natural that

they attract tourists to the area, bringing in some

economic value.

• Places close to volcanic activities tend to have

higher potential for geothermal energy, which can

be an advantage to the towns and cities.

• Some ash and lava breakdown become soils that

are rich in nutrients, and become good areas for

crop planting activities.

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The positive effects of volcanoes eruption E

Definition of Explanation Text

A. Definition

Explanation is a text which tells processes relating to forming of

natural, social, scientific and cultural phenomena. Explanation

text is to say ‘why’ and ‘how’ of the forming of the phenomena.

It is often found in science, geography and history text books.

B. Purpose

purpose of the text is to explain the processes that occur in the

formation or activity associated with natural phenomena, social,

scientific, cultural, and others aimed at explaining.

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C. Generic Structure

General statement; stating the phenomenon issues which are

to be explained.

Sequenced explanation; stating a series of steps which

explain the phenomena.

D. Language Features

1.Focusing generic participant; daylight.

2.Using chronological connection; then, so, but.

3.Using pasive voice; you would be forgiven.

4.Using present tense; the earth is actually closer to the sun.

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Thanks for your attention….

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