For an explanation, see the main splats page
- Earthquakes happen all the time, all over the Earth. Most are too small or too far away for us to feel them, but they can be measured with instruments.
- Earthquakes happen when there is movement along planes of weakness called faults in the Earth's crust, when built-up tension is released suddenly.
- Earthquakes happen as a result of tension or compression within or between plates, leading to slippage of large masses of rock along planes of weakness.
- Major earthquakes happen at faults where tectonic plates slip past each other and at subduction zones where one plate is slipping downwards under another.
- An earthquake is a shock wave that results from sudden movement when a build-up of tension is released because something gives way, releasing energy.
- Under some circumstances, rocks will move past each other along a joint plane. When two blocks of rock move, relative to each other, a fault is formed.
- The surface of the earth is made up of plates in motion, and earthquakes often happen at plate boundaries, where two plates are in relative motion.
- In 1760, John Michell suggested that an accurate timing of the arrival of the waves could help locate the center of an earthquake that had happened elsewhere.
- Earthquakes travel through the Earth as waves, following several different paths, and arriving at seismographs at different times, so the source can be located.
- Structures beneath the earth's surface are mapped either by using the information coming from earthquakes, or by looking at the reflections of small explosions.
- Earthquakes may be placed on a scale of intensity, either on the basis of the damage done at the epicenter, or in terms of the energy released.
- Points recording the same earthquake intensity are joined by an isoseismal line: in early times, these showed scientists the location of the epicenter.
- In 1935, Charles Richter invented a logarithmic scale to measure the strength of earthquakes, mainly based on the energy released in the quake.
- Seismology depends on the use of instruments to get intensity measures for earthquakes, using either the Richter scale or the modified Mercalli scale.
- Tsunamis are typically caused either by sudden underwater block movements in earthquakes, or when large blocks come off the side of undersea volcanoes.
- A tsunami is a water wave generated by sudden earth movements. Tsunamis may travel thousands of kilometers as barely visible waves before hitting a coast.
- In shallow waters, a tsunami builds up to a considerable height, and may flood a large coastal area, without any warning, far from any seismic activity.
This file is http://members.ozemail.com.au/~macinnis/scifun/splatsquakes.htm, first created on January 25, 2006. Last recorded revision (well I get lazy and forget sometimes!) was on January 25, 2006.
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