eed that S waves can travel, they can not pass through the liquid materials. Earthquake magnitudes are expressed on the Richter scale, and measure the amount of energy released. Seismograph, an important geological instrument, record earthquake waves. According to this, scientists can predict what kind of waves will come up to surface and for how long. Of the million or so earthquakes per year, strong enough to be noticed, only few release enough energy to do serious damage. About 10 extremely violent earthquakes occur each year on the average but only one of them happens to be involved in a populated urban area. " The most destructive earthquake or record occurred in 1556 in Shensi Province in China, where an estimated 830,000 people died. Those people lived in Cave dwellings excavated in losses, which collapsed as a result of the quake. The Catastrophic effects of earthquakes are generated in four main principal kinds: Ground motion, which damages or sometimes completely destroys building. Although, today, modern Engineering in order to prevent such damage has given many solutions to the problem, in very strong earthquakes there is no possible structure of safety. The ground motion causes fires not only, because it breaks the gas lines but also because it displaces the electrical wires and stoves. Most damages are caused by structural failures or by fire. Another major cause of destruction is landslides this is when large amounts of earth slide off a hillside. Because of theses, almost all structures are destroyed by rapidly moving regolith (layer of earth). Finally the seismic sea waves causes movement of the sea floor. These waves are called tsunami. These huge waves have struck Hawaii and destroyed everything in their path. The destructiveness of quake is determined by such factors as velocity, acceleration period and duration or the earthquake waves. The size, shape, material and quality of construction of building are the most im...
