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1. Tectonic plates are pieces of the Earth's crust and upper mantle that move and interact with each other. There are several major tectonic plates and many minor ones. These plates are constantly moving and shifting, which can cause earthquakes, volcanic eruptions, and other geological phenomena.
2. The Earth is made up of several layers, including the crust, the mantle, and the core. The crust is the outermost layer and is relatively thin, making up just a small fraction of the Earth's total mass. The mantle is the layer beneath the crust and is much thicker. It is made up of solid rock that is hotter and more dense than the crust. The core is the innermost layer of the Earth and is made up of two parts: a solid inner core and a liquid outer core.
3. A hypocentre, also known as the focus of an earthquake, is the point within the Earth's crust where an earthquake originates. It is the location where the energy released during an earthquake is first transmitted to the surface of the Earth.
4. A seismograph is a scientific instrument used to measure and record earthquakes. It consists of a seismometer, which is a device that measures ground movement, and a recording device, which records the data collected by the seismometer.
5. There are approximately 500,000 earthquakes that occur worldwide each year, although most of these are too small to be felt by people. The number of earthquakes can vary greatly from year to year and can be influenced by a variety of factors, including tectonic plate movement, volcanic activity, and other geological processes.