After reading these slides, you will be able to understand basics of Volcanoes

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2. Tectonic plates
 “A ‘Volcano’ is a mountain from which hot melted
rock ,ash , gas and steam collectively called ‘‘‘ lava
’’’ bursts out”.
 The word Volcano is derived from a Roman Word
“Vulcan”, the name of Roman god of fire.
 Volcanoes are mostly found on the meeting point
of “Tectonic Plates”.
 Now, here a question raise in our mind that ;
 What are the Tectonic Plates ?
 Answer :
 These plates are simply the pieces of
Earth’s surface. The plates are also called
“Lithospheric plates”.
 The plates are joined together like a jigsaw puzzle.
 The horse-shoe like area of pacific ocean known
as the “Ring of Fire”, which is spread on the area
of 40,000 km, has 90 % of all volcanoes in the
Earth.
 About 1,900 Active Volcanoes are present in Earth
that are considered to be explode again.
 In 1883, named Krakatau erupted in South Asia
releasing 200 megatons{Unit of energy } which is
equal to the energy of 15000 nuclear bombs.
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3. Interesting facts of Volcanoes :
 Volcanoes don’t only occur on land, they also
occur in ocean’s floor and under ice-caps.
 Around 350 million people live in the zone of
active volcanoes.
 Magma :
 The hot liquid rock inside the
Volcano is called Magma.
 Lava :
 Magma that reaches the Earth
surface is called lava.
 Lava’s temperature is 1,250 degree
centigrade.
 Any thing that come in the way of lava is
burnt.
 If you used a glass thermometer to detect
the temperature of lava it would melt.
 Metals like Nickel alloys, iron alloys, tungsten
and molybdenum alloys are capable to resist
lava.
 The lava is technically wet, but we don’t say
it wet normally.
 Volcanic Eruption causes these deadliest
disasters :
 Tsunami ; A long high sea wave caused by
Earthquake.
 Floods ; An overflow of water beyond it’s
limits.
 Earth-quakes ; A sudden and violent shaking of
ground.
 Mudflow ; A hardened flow of mud.
 Rock-falls ; A sudden arrival of a loose Rock.
 Lava is a liquid So, this state of matter makes it
technically wet and the rocks over which it flow
,are technically wet by lava.
 There are 2 major types of lava ;
 Acidic lava : Basic lava :
 This lava type This lava type is non-
is viscous and viscous , darker in
lighter in color, color and has lower
and has high Silica content.
Silica content.
 The lava can’t melt a Diamond but it can burn it .
 The lava is 3 times denser than water, humans
are also made up of mostly water So, a human is
also 3 times denser than lava. Hence, according
to the law of physics, a human being can not sink
in lava but it can float on it.
 Lava quickly cools down but it takes 10-15
minutes to walk on it but the lava flow itself takes
many months to cool down.
 Now there is another question that
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4.  Raise in our mind that :
 What would happen when lava meets the sea ?
 Answer ;
 “When fresh lava is dripped in sea,
newly happened in Hawaii 26 June, 2018 at 6 in
the morning ,the lava quickly cools down boiling
the sea into steam.
 There are 3 types of Volcanoes :
 Active Volcano ;
 In this type of a volcano Eruption
can occur at anytime and often.
 Dormant Volcano :
 In this type of Volcano, that
doesn’t erupted for many years but expected to
erupt anytime in future.
 Extinct Volcanoes :
 The Volcanoes which erupted
many years ago and expected to no eruption in
future.
 There are 4 different shapes of Volcanoes:
 Shield Volcanoes :
 Also called flat Volcanoes. If
the magma is runny, the gas will escape easily
and no explosion will occur. The magma just
comes out of the volcano and flows down the
slides.
Shield volcanoes are shaped like a bowl
.The examples include the Mount-Etna and the
Mountains of Hawaii.
 Composite Volcanoes :
 The volcano’s shape is tall
and thin .If the magma is thick and sticky like honey .
Hence, the gas explodes inside the volcano. The
composite volcano is also known as “strato-
Volcanoes”. The examples are Mount Fuji and Mount
Hood.
 Cinder Cones Volcanoes :
 These Volcanoes are
Oval-shaped and Circular built from erupting lava
,when small pieces of lava cool down they form
cinders around the vent of the volcano. Examples
are Lava Butte and Paricutin.
 Lava Domes :
 Lava domes are formed when lava is
too thick to flow and makes a steep-sided
aggregation as the lava piles up near the vent.
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5. Shield Volcano Mount Etna
Mount Fuji Lava Butte 5

6. Kelud Lava Dome 6

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