Why are there Earthquakes?
Posted on 02. Nov, 2010 by raiders1 in Nature
An earthquake happens when the earths plates are either moving apart or are rubbing against eachother. Tectonic plates are made up
of rigid bodies which move together on the surface of our earth. These are made up of both the continental and oceanic crusts and are moving together. The continental crust is made up of a light mass like granite. The oceanic crust is made up of heavy and ironrich rock which is called basalt.
When an earthquake happens, there is an elastic energy that is released and they send out alot of vibrations that travel all through the earth. The vibrations are also known as the siesmic waves. There is a place deep within the earth called the focus, this is where the siesmic waves are generated by the release of the stored elastic energy. The epicenter is the exact point on the earths surface directly above the focus.
Scientists use a scale called the Richter Scale. This scale can measure an earthquakes strength. The higher the number on the Richter Scale means that the earthquake is more destructive and forceful like the earthquake that shook in the year of 1906 which caused many fires that burnt down most of San Francisco. Lights that hang can start to swing at a level 3 on the Richter Scale. Windows start to break at a level 5 and Bridges and Buildings start to collapse when the Richter Scale hits a level 7. A Tsunami can also be caused by the sudden vertical offset of the ocean floor caused by an earthquake.
Popularity: 1%
