|
|
pastorstaff.faithweb.com |
|
Causes Most earthquakes are powered by the release of the stresses that accumulate over time, typically, at the boundaries of the plates that make up the Earth's lithosphere. The most severe of these earthquakes are located along compressional and translational plate boundaries. Deep focus earthquakes are possibly generated as subducted lithospheric material catastrophically undergoes a phase transition at depths greater than 600 km. Some earthquakes are also caused by the movement of magma in volcanoes, and such quakes can be an early warning of volcanic eruptions. A rare few earthquakes have been associated with the build-up of large masses of water behind dams, such as the Kariba Dam in Zambia, Africa, and with the injection or extraction of fluids into the Earth's crust (e.g. at certain geothermal power plants and at the Rocky Mountain Arsenal). Such earthquakes occur because the strength of the Earth's crust can be modified by fluid pressure. Finally, earthquakes (in a broad sense) can also result from the detonation of explosives. Thus scientists have been able to monitor, using the tools of seismology, nuclear weapons tests performed by governments that were not disclosing information about these tests along normal channels. Earthquakes such as these, that are caused by human activity, are referred to by the term induced seismicity. Another possibility to explain earthquakes is related to gas movement in the earth's interior, mainly methane (see related topics [[1] (http://www.people.cornell.edu/pages/tg21/Earthq.html); [[2] (http://www.people.cornell.edu/pages/tg21/eyewit.html)).
Main Pastor1 Pastor2earth1 earth2 earth3 earth4 earth5spanishhealth1
|