This VDO clip talks about earthquakes.An earthquake is a vibration that travels through the Earth's crust. The lithosphere is broken up into plates .Quakes can be caused by the plates to move in different , and a variety of things, including meteor impacts and volcanic eruptions. But most naturally occurring earthquakes are caused by movement of the Earth's surface. Where plates collide, rock layers are forced upwards creating mountains. Lava emerges from the mantle and cools to form new section of crust when plates diverge between earth's surface layers.
However, our planet's seemingly stable surface is made up of enormous pieces of rock that are slowly but constantly moving. Those pieces continually collide with and rub against one another, and sometimes their edges abruptly crack or slip and suddenly release huge amounts of pent-up energy. The stored energy is released in the form of an earthquake. An earthquake emits its power as three waves of energy . Primary, or waves are felt as a sudden jolt . Secondary , or S-waves arrive a few seconds later and are felt as a more sustained side- to- side shaking. S-waves and P-waves are two types of wave with different movements.
The earthquakes that capture our attention are the rare big ones that strike near heavily populated areas. Such earthquakes have caused a great deal of property damage over the years.and they've claimed many lives.