Know More: Natural Disasters


We are blessed to live on a beautiful planet, Earth—the only planet that supports life. Around us we have awe inspiring, picturesque landscapes and indescribable beauty. But our planet also has a dangerous side where changes in its crust and atmosphere can cause natural disasters like floods, tornadoes, hurricanes, volcanic eruptions, earthquakes, heat waves and landslides. Let’s take a look at some natural disasters

An earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves. Seismic waves are massive vibrations that occur when the Earth’s tectonic plates collide against each other. Earthquakes are recorded with a seismometer, also known as a seismograph. The zone where an earthquake occurs is known as the fault zone. The magnitude of an earthquake is accurately reported on the Richter scale. Magnitude 3 or lower earthquakes are considered minor whereas earthquakes of magnitude 7 or more can cause serious damage over large areas. Earthquakes cause shaking and displacement of the Earth’s surface. The deadliest earthquake in recorded history is the one that took place in the Shensi province in China on June 23, 1556, which killed an estimated 8,30,000 people.

A tsunami is a series of waves created when a body of water, such as an ocean, is rapidly displaced. An earthquake usually precedes a tsunami. Events that take place after a tsunami can include mass movements above or below water, landslides, volcanic eruptions and other underwater explosions. On March 11, 2011, a powerful tsunami shattered the north eastern coast of Japan. It claimed the lives of thousands of people and displaced several more. Heavy loss of mankind was reported as the tsunami also triggered nuclear disasters at various places.

A flood is an overflow of water that submerges land. Floods occur when the volume of water within a body of water such as a river or lake exceeds the total capacity of the body. As a result, some of the water flows or sits outside of the normal perimeter of the body. Floods can also occur in rivers when the strength of the river is so high that it flows right out of the river channel, usually at corners or meanders. Severe flooding occurred during the 2011 monsoon season in Thailand. The floods began at the end of July and the flooding soon spread through the provinces of Northern, Northeastern and Central Thailand along the Mekong and Chao Phraya river basins. 13.6 million people were affected by these floods and several farmlands were destroyed.

Hurricanes or tropical cyclones are a series of cyclonic storm systems that form over the oceans. These are caused by evaporated water that comes off the ocean and becomes a storm. The Coriolis Effect causes the storms to spin and when this spinning mass attains a wind speed greater than 120kms per hour, a hurricane is formed. In August 2005, Hurricane Katrina devastated the city of New Orleans, USA. The hurricane began as a tropical depression over the Bahamas and gained significant strength as it moved towards Florida. 1,800 people lost their lives as a result of the hurricane and more than 1 million people along the Gulf Coast were displaced when their homes were destroyed.

Drought can be defined as a condition of unusually dry climate within a certain geographic region due to lack of annual rainfall. Drought is a natural disaster, which is hazardous to human beings as it results in water shortages, causes damage to crops and increases the death rate of livestock and wild animals. Drought also results in shortage of electricity. In the Horn of Africa, the 1984 drought led to a famine which killed 7,50,000 people.

An avalanche is a hazard involving a slide of large amounts of snow or rock mass down a mountainside, caused when a buildup of material is released down a slope. It is one of the major dangers faced in mountainous areas during the winter. As avalanches move down a slope, they may gather snow from the snowpack and grow in size. The snow may also mix with the air and form a powder cloud. A powder cloud is a turbulent suspension of snow particles that flows with the gravity current. Avalanches kill an average of 200 people each year.

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