Essay, Paragraph or Speech on “Volcanoes and Earthquakes” Complete Essay, Speech for Class 10, Class 12 and Graduation and other classes.

Volcanoes and Earthquakes

Earthquake—The sudden trembling of earth caused by sudden slippage of rocks along the faults in the crust. The faults are fractures in the rock body along which there has been an observable amount of displacement.

These faults sometimes reach the ground surface displacing the objects on the ground. The Earthquake wave which are produced due to sudden or abrupt deplacement or slippage of rocks travel outward in all directions. Gradually they lose their energy. Thus earthquake is completely crustal phenomenon.

Earthquakes are vibrations in the earth’s crust caused by ruptures and sudden movements rocks that are strained beyond their elastic limits of earthquake.

Focus—The originating point of earthquake inside the earth’s crust is called focus. Epicentre—It is a point on the earth’s surface vertically above the focus. It is this point where trembling is the strongest.

List of Major Earthquakes

The Sanfrancisco Earthquake                 1906

The Assam                                                    1897

The Bihar                                                      1934

Quetta                                                           1935

The Gujrat                                                    2001

The Tsunam                                                 2004

The Iran                                                        2003

The Turkey                                                   1997

The Russian                                                  1989

 The Kashmir                                                2005

Major Causes of Earthquakes Plate Tectonics—The theory of plate Tectonics postulates that outer lithospher which is rigid has mosaic of rigid segments called plates. These plates move on the plastic upper mantle (asthenosphere) on which oceans and continents rest. This sometimes causes vibration in the lithosphere resulting in the occurance of quake.

Volcanic eruption—Sudden volcanic eruptions create vibrations in the earth’s crust causing violent earthquake.

Major Earthquake Tones-1. The Circum Pacific Zone—About 66% of total earthquakes have been recorded in this zone.

2. The Mid Atlantic Zone—Divergent plate boundary, Volcanism and sea floor spreading over it make it quake prone.
3. Mid-Continental Zone—This zone extends from Alpine mountain system to Himalaya system.
4. Interplate Earthquake Zone—Indian peninsula is prone to interplate earthquake.

Volcanoes—Volcano is the coming out the molten material from the crust of the earth through a vent or pipe which is connected to underlying magma (molten material) chamber. When this molten material or magma is accumulated around the pipe in the form of a mound it is called volcano. The molten material or magma is brought to the surface in the form of volcanic fragments which are commonly known as lava. The temperature of lava ranges between 800° and 13000° celsius.

Causes of Volcanoes—Rocks are found in solid state in the earth’s crust because of overlaying pressure from the rock above it. When a crack is developed in rock or earth that is lying above. This causes melting of hot rocks into liquid in small chambers commonly known as magma chambers. Magma (molten material) finds its passage in the zones of weakness, regions of reduced pressure and fissures. Gaseous pressure in some pockets of the earths crust forces magma out. While taking a passage upward it all causes melting of overlying rocks.

Types of Volcanoes on the Basis of Frequency—There are three types of volcanoes on the basis of frequency.

1. Dormant Volcano—Those volcanoes which cruptintermittently are called Dormant Volcano. Fijiyama of Japan, Mt. Visuvius of Italy, Karakota of Indonesia and Barren Islan of Andman& Nicobar are examples of Dormant volcanoes.

Active Volcanes—Those volcanoes which crupt frequently are active volcanoes.

Extinct Volcanoes—Those volcanoes which have not erupted for a very long time but have a record of eruption in the past are extinct volcanoes.

 Volcanic Features

 Volcanic vent—Volcanic vent is an opening or passage through which lava comes out.

Crater—Around the vent when extrusion of lava takes place, a saucer shaped depression is formed which is called crater. Caldera—Caldera is the enlarged form of crater.

Pyroclastic Material—Rock and mineral fragments which are blown out along with lava from a volcano are known as pyroclastic materials.

Volcanic Bombs—pyroclastic material in solid spindle and spherical shape are known as volcanic bombs.

Spatter Cone—When lave gets accumulated near the vent after being thrown in the air it forms spatter cone.

Volcanic Lapilli—Particles of lave which varies in siz from 4 to 25 rmm. are known as volcanic lapilli. Volcanic

Dust or Ash—Particle in size under 4 mm. are known as volcanic ash or dust.

Tuft—When volcanic ash remains suspende for a long period of time after being thrown up in the air, it is either taken away by wind or falls with rainfall. Finally it is drifted away by running water and gets deposited as sedimentary layer known as tuff.

On the Basis of Style of Eruption

Types of Volcanoes—There are two type of volcanoes on the basis of style of eruption.

Types of Fissure Eruption—When volcanic material or lava come out from a fissure or group of fissures it freely flows away from the fissures and does not form cones. Deccan traps in India, Columbia Plateau (U.S.A.), Antrum plateau (Ireland) are the examples of such type of volcanic eruption.

Central (Explosive) Type of Eruption—When lava emanates from central vent or pipe forming a cone. Such style of eruption is known as central (Explosive) type of eruption. Examples of such eruptions are Hawain plateau (U.S.A.)

Active Volcanoes of The World

Volcano                                                                       Location                    Country

1. Ojas Del Salade (highest) Andes Argentina Chile
2. Guallatiri Andes Chile
3. Cotapaxi Andes Ecudor
4. Tapungatito Andes Chile
5. Lascor Andes Chile

6 Navadodelviz                                                         Andes                                    Colombia

7 Sangay                                                                     Andes                                    Ecuador

8 Popocatepiti                                                     Altiplano de Mexico                       Mexico

9. Tacana Serria Madre Geetmala
10. Fuego
11. Purace Andes Colombia
12. Klyvchevskaya Kanchatka Penin
13. Soplea Kanichatka Peninsula
14. Wrangelli Wrangli Mts. Alaska
15. JajumulcoGuetamalaGuetmala
16. Mt. Cameroom Monarch Is. Cameroon
17. Erebus Ross Island Antarctica
18. Rind jani Lombok Indonesia
19. Pico de Te-Teide Canary-Island Spain
20. Semeru Java                            Indonesia
21. Nyiragongo Verunga Zaire
22. Karyakaskya Kamchatka Peninsula
23. Irazu Cordellera Costa Central
24. Salmat Java Indonesia
25. Mount Spurn Alaska range U.S.A.
26. Mont Etna Sicily Italy
27. Agung Bali Indonesia
28. Kilauae Hawaii U.S.A.
29. Stromboli Islands Mediterraneon
30. Surtesey Iceland
31. Ana Karakota Island Indonesia

Volcanic Zones

Zinc                                                                            Location

1. Circum Specific Belt (Ring of Fire) From Erebus of Antarctic and run northward through Andes and Rockies and come to end to Volcanoes of Island arc (Which include Kamchatka), Japan. Phillipines etc.
2. Mid Atlantic Zone Along Mid, Atlantic ridge; include Iceland (which is most active volcanic are in this zone) St. Helena, Azores Island etc.
3. Mid-Continental Zone Include Alpine Mountain chains, Mediterranean Sea and Eastern Africa.
4. Intra-Plate Volcanic Zone Hawaiia Volcanic chain, Reunion island Rhine Graben.