Earth's crust is divided into a number of fragments, known as tectonic plates. These plates are in constant motion and it has been found that most of the earthquakes take place along the plate boundaries (regions where tectonic plates meet each other). Such earthquakes are known as interplate earthquakes. There are few instances of earthquakes within a given tectonic plate and such earthquakes are known as intraplate earthquakes. Some of the major earthquake-prone regions of the world include, margins of Pacific Ocean, boundary of Eurasian and Arabian plates, boundary of Indian and Australian plates, etc. One way to determine the intensity of the earthquake is by using Richter scale. On this scale, any two successive values are separated by a factor of 10. Thus, an earthquake of intensity 6 is 1000th time that of intensity 9 earthquake.
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