Natural Calamities - Volcano - video Dailymotion

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00:00Hi kids, today we will learn about a natural disaster that is a volcano.

00:11So let's get started.

00:14Before learning about volcanoes, we need to learn what are layers of the earth, what are

00:21fault lines, and what are tectonic plates.

00:27So let's first learn about the layers of the earth.

00:32The earth is made up of three layers.

00:37The outer crust is a layer on which we live.

00:42It is estimated to be about 1,800 miles deep.

00:49Then there is the mantle, and then the core, or the inner and outer core.

00:57The mantle, that is the outer core, is made up of molten material and gases.

01:06Molten materials are solids, like rock, that have turned into liquids because of extreme

01:14heat.

01:16The name of molten rock, and other gases in the earth's mantle, is magma.

01:25Magma is liquid made up of many crystals, fragments, and gases.

01:33When they cool off on the earth's surface, they turn into magmatic, or igneous, rocks.

01:42Now let's learn what are fault lines.

01:46Fault is a planar fracture in earth's crust.

01:51They result from action of tectonic plates.

01:57Tectonic plates are pieces of the earth's crust, and the uppermost mantle, together

02:05referred to as the lithosphere.

02:10Now we know what are the layers of earth, fault line, and also what are tectonic plates.

02:20So now we are ready to learn what is a volcano.

02:27A volcano is an opening, or vent, in the earth's topmost layer, called crust.

02:35Through this opening, extremely hot mixture of gases, lava, ash, and other burning substances

02:45called lava, comes out.

02:51Volcanic eruptions create elevations that look like big mountains.

02:58Volcanoes occur at weak zones, or points in the earth's crust.

03:05Now let's learn various parts of volcanoes.

03:10Magma, molten rock material, which is beneath the earth's surface, is called magma.

03:21Lava, molten rock material, when it comes out of the earth's surface, it's called lava.

03:31And on solidification, this lava turns into igneous rocks.

03:40Vent, an opening in the earth's surface through which volcanic materials escape, is called

03:48vent.

03:50A vent is not visible in a volcano.

03:56The visible opening is called crater.

04:01It is the mouth of the volcano.

04:06This crater surrounds the volcanic vent.

04:11Ash, fragments of lava or rock smaller than 2 millimeters in size, that are blasted into

04:21the air by volcanic explosions, is called as ash.

04:28Ash cloud, a cloud of ash formed by volcanic explosions.

04:36Now let's see how and why volcanoes erupt.

04:42Sometimes extreme pressure builds up across the fault lines, and a sudden eruption occurs,

04:52and molten matter and ash comes out of the opening in the earth, which is called vent.

05:03When the molten matter is still inside the earth, we call it magma.

05:10And when it comes out of the earth's surface, we call it lava.

05:17Lava can be as hot as 2,200 degrees Fahrenheit.

05:23It is red hot when it comes out of the vent, and turns gray or black when it cools down.

05:33Some volcanoes are very, very violent, and some are not as violent.

05:41There are different types of volcanoes all over the earth's surface.

05:48Volcanoes exist even beneath the ocean.

05:53On the ocean beds, common gases that comes out of the volcanoes are water vapor, carbon

06:03dioxide, sulfur dioxide, hydrogen chloride, and hydrogen fluoride, and hydrogen sulfide.

06:14Now let's learn about some recent volcanic activities.

06:20Some active volcanoes exist in Iceland, Hawaii, Indonesia, Ecuador, and Mexico.

06:34Volcanoes in Philippines and Papua New Guinea have recently calmed down.

06:43There are about 500 active volcanoes on the earth.

06:50The most active and biggest volcano on the earth is Mauna Loa volcano.

06:58Though we call volcano a natural disaster, but unlike floods, wildfires, earthquakes,

07:08and avalanches, volcanoes are not as bad as they seem.

07:16They have some positive effects to them, too.

07:21Let's see some positive effects of volcanoes.

07:26Volcanoes create scenic beauty and also attract tourists, so it becomes a tourist destination.

07:35Areas near volcanoes become very good sources of geothermal energy that can be tapped to

07:43produce electricity and many more purposes.

07:50The surrounding areas of volcanoes also become rich in nutrients, and the soil becomes much

07:58more fertile.

08:01Now let's learn some negative effects of volcanoes.

08:09The area where volcanoes erupt becomes devastated, that is, it destroys life and property.

08:20Ash that comes out of volcanoes has very bad effect on the ozone layer.

08:28The previous landscape and natural beauty of the place is destroyed.

08:36So kids, today we learned a lot about volcanoes.

08:41Now you may go ahead and take a quiz to learn more.

08:45Bye-bye!

Natural Calamities - Volcano

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