Earthquakes, also known as temblors, occur when the tectonic plates of the earth move while floating on the molten rock that is earth’s core. These tectonic plates, at times, collide against each other and affect the earth’s surface; these effects can either be drastic or barely felt. The tectonic plates create immense stress which, when released, sends seismic waves or vibrations across the earth’s surface. Lasting from few seconds to minutes, these earthquakes are followed by aftershocks which are sometimes more intense than the main quake. Among the countless quakes that hit the earth’s surface, only 20% are destructive while others cause only mild tremors. However, these tremors are quite unpredictable and occur anywhere, at any time. Though most of the earthquakes occur due to the plates’ collision, even volcanic eruptions and meteorological crashes can trigger such tremors. 75% of the world’s earthquakes occur in a region called ‘Pacific ring of Fire’. This region has plenty of fault zones in its tectonic plates which lead to frequent clashes. Read on to know more about the interesting facts about earthquakes and their occurrence.
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There are about 20 moving plates which form the earth’s surface. When these plates collide with each other, breakage and stress in earth’s crust can be seen and felt. With this stress, energy is released as seismic waves that we experience as earthquakes.
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As per U.S Geological survey, more than three million earthquakes occur every year, averaging to about 8000 quakes in a day and 11 in every second. The number of people who die due to earthquakes every year is more than 10,000. However, only 100 earthquakes actually cause any serious damage.
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A normal earthquake lasts 60 seconds.
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The earthquake which occurred in Indian Ocean on December 26, 2004 was of the magnitude 9.0 and killed almost 160,000 people.
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The ‘focus’ of an earthquake is the point where it actually starts while epicentre is a point on the surface of the earth, directly above the focus.
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Earthquakes generate two types of waves, viz., body waves and surface waves. The time of the arrival of the various body waves enable the seismologists to locate the epicentre.
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An earthquake which occurs after the main quake is the aftershock. In few cases, these aftershocks are more intense than the main quake.
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Experts use Richter scale and Magnitude scale to analyse the amount of energy released during a quake.
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The study of earthquakes is known as seismology. Seismograph, used to measure, detect and record the vibrations of earthquakes, was invented in 1751.
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One of the most lethal earthquakes occurred in Shansi China in 1556 when 830,000 people died due to the tremors. The deaths occurred mainly due to the collapse of the caves that people lived in. The most deadly earthquake of recent times occurred in Sumatra in 2004 where almost 255,000 people died.
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The largest recorded earthquake occurred in Chile in 1960 with a magnitude of 9.2 on Richter scale.
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Earthquakes occur on moon as well and are called moonquakes. However, these are of lesser magnitude and smaller in comparison to those that occur on earth.
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Alaska, in United States, is the most earthquake prone region in the world. An earthquake, with a magnitude of 8, occurs once in every fourteen years here.
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The occurrence of earthquake is not dependent on weather which means earthquakes can occur in any type of weather.
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Countries like Japan use great defence mechanisms while constructing houses to make them earthquake resistant. Good engineering prevents the collapse of buildings during earthquakes.
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Animals can sense earthquakes much before they occur.
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A normal earthquake has a depth of 50 miles below earth’s surface.
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Around 10,000 earthquakes occur every year in Southern California in United States.
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It was Aristotle, the Greek Philosopher, who found out that soft ground shakes more during earthquakes than hard grounds.
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During large earthquakes, people experience a swaying or a jerking motion followed by a pause and then a strong jerking.
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In urban areas, the earthquakes cause more destruction as the seismic waves can weaken the manmade structures and force them to collapse.
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The peaks in the Himalaya-Karakoram mountain ranges were formed due to the moving of the tectonic plates millions of years ago. Similar movements can now be felt in the Andaman & Nicobar regions of India.
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Though the exact prediction of earthquake is far from being achieved, gathering information and data from the previous quakes enable the scientists to predict the future quakes to a certain extent.