23-05-2017, 03:23 PM
i need a project
normal project of class 9th of cbse
i need a project
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class 9th project on earthquake
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i need a project
normal project of class 9th of cbse
i need a project
27-05-2017, 01:08 PM
An earthquake (also known as tremor or tremor) is the tremor of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can vary in size from those who are so weak that they can not feel violent enough to drive people around and destroy whole cities. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.
Earthquakes are measured using seismometers. The magnitude of the moment is the most common scale in which earthquakes larger than about 5 are reported for the entire globe. Earthquakes more numerous than magnitude 5 reported by national seismological observatories are mainly measured on the scale of local magnitude, also known as the Richter scale. These two scales are numerically similar in their range of validity. Earthquakes of magnitude 3 or less are mostly imperceptible or weak and magnitude 7 and above can cause serious damage to larger areas, depending on their depth. The largest earthquakes in historical times have been of magnitude slightly over 9, although there is no limit to the magnitude possible. The agitation intensity is measured on the modified Mercalli scale. The lower an earthquake, the more damage it will cause to the structures, all the others being equal.
On the surface of the earth, earthquakes manifest themselves by shaking and sometimes displacing the ground. When the epicenter of a major earthquake is on the high seas, the seafloor can be shifted enough to cause a tsunami. Earthquakes can also cause landslides, and occasionally volcanic activity.
In its most general sense, the word earthquake is used to describe any seismic event - whether natural or caused by humans - that generates seismic waves. Earthquakes are mainly caused by the breakdown of geological faults, but also by other events such as volcanic activity, landslides, mine explosions and nuclear tests. The initial break point of an earthquake is called a focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.
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