An earthquake is a phenomenon that results from the sudden release of stored energy in the earth’s crust that creates seismic waves. At the earth’s surface, earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes tsunamis, which may lead to loss of life and destruction of property.

Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic event-whether a natural phenomenon or an event caused damage that generates seismic waves.

Types of Earthquakes

Naturally occurring earthquakes and induced earthquakes. The consequences of both natural and human induced hazards are worst for the earth’s creatures and landscape.

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The meaning of hazards is something that is potentially very dangerous. In the beginning, hazards were believed to be natural only, in which earthquakes were highly dangerous and unavoidable. The present dimensions of hazards are also evolved with the human induced activities, which include large-scale depletion of forests, emission of major green house gases into the atmosphere, and high rate of technically developmental activities. Among natural hazards, earthquakes are the worst and most widespread natural hazards and cause damage to human life and vegetation and loss of crop production. Selected largest earthquakes, by magnitude on the Richter scale are given in.

Selected Largest Earthquakes, by Magnitude on the Richter Scale

Year

Location

Magnitude

1755

Lisbon, Portugal

9.0

1906

Andes (Colombia)

8.6

1906

Valparaiso, Chile

8.4

1906

San Francisco, United States

8.25

1911

Tienshan, China

8.4

1920

Kansu, China

8.5

1923

Tokyo,Japan

8.2

1933

Japanese trench

8.5

1950

North Assam, India

8.6

1960

Chile

8.3-8.9

1964

Alaska

8.6

1976

Tangashan, China

8.2

1977

Sumba, Indonesia

8.9

1977

Argentina

8.2

1979

Indonesia

8.1

1985

Mexico City, Mexico

8.1

1994

Bolivia

8.2

2000

Bhuj, India

8.0

2004

Northern Sumatra

9.0