| | Natural Hazards Causes and Effects Lesson 2 Earthquakes: University of Wisconsin Disaster Management Center (Site not responding. Last check: 2007-11-06) |
 | | Earthquakes are caused by the movement of massive land areas, called plates, on the earth's crust. |
 | | The frequency and amplitude of the vibrations produced at the surface, and thus the severity of the earthquake, depend on the amount of mechanical energy released at the focus, the distance and depth of the focus, and the structural properties of the rock or soil on or near the surface. |
 | | It is not uncommon in the aftermath of an earthquake to see an increase of land invasions, major shifts of population from rural to urban areas, and a decline in the number of skilled workers in rural areas. |
| dmc.engr.wisc.edu /courses/hazards/BB02-02.html (6459 words) |