Posts Tagged seismic waves
Earthquake Resistant Structures | Engineering Tips
Posted by Architect in Earthquake Engineering on June 15, 2010
Earthquakes are a major geological phenomena. Man has been terrified of this phenomena for ages, as little has been known about the causes of earthquakes, but it leaves behind a trail of destruction. There are hundreds of small earthquakes around the world everyday. Some of them are so minor that humans cannot feel them, but seismographs and other sensitive machines can record them. Earthquakes occur when tectonic plates move and rub against each other. Sometimes, due to this movement, they snap and rebound to their original position. This might cause a large earthquakes as the tectonic plates try to settle down. This is known as the Elastic Rebound Theory.
Haiti Earthquake 2010
Every year, earthquakes take the lives of thousands of people , and destroy property worth billions. The 2010 Haiti Earthquake killed over 1,50,000 people and destroyed entire cities and villages. Designing Earthquake Resistant Structures is indispensable. It is imperative that structures are designed to resist earthquake forces, in order to reduce the loss of life. The science of Earthquake Engineering and Structural Design has improved tremendously, and thus, today, we can design safe structures which can safely withstand earthquakes of reasonable magnitude.
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Types of Seismic Waves
Posted by Architect in Earthquake Engineering on June 15, 2010
During fault ruptures which cause earthquakes, the sudden breakage and movement along the fault can release tremendous amount of energy. Some of this energy is used up in cracking and pulverizing the rock as the two blocks of rock separated by the fault grind past each other. Part of the energy, however, speeds through the rock as seismic waves. This waves can travel for and cause damage at great distances. Once they start, these waves continue through the earth until their energy is used up.
There are two basic types of seismic waves, and they travel at different speeds through earth. The faster p waves and the slower s waves.
Primary or push waves or P waves
Primary Waves
These are longitudinal in nature like sound waves. The velocity of P waves is highest about 5.4 km/s and depends on the density of the rock and resistance to compression. P waves can pass through liquids also.
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