|MadSci Network: Earth Sciences|
Hi! You were wondering why some places get "hit" by earthquakes time and time again. And some places don't seem to feel a quake at all. Sorry I've taken so long in replying, I'll do what I can. Are you familiar with "plate tectonics?" The cut-and-dry explanation of earthquakes is that most of the land and ocean bottoms "float' around on the more fluid parts of the earth and crash into each other in many ways. Sometimes, as the plates pull apart or stretch out, an earthquake can also happen. I like this site- it's got little movies you can click on to learn more about tectonics and how plates move. http://scign.jpl.nasa.gov /learn/plate4.htm This is a link to a map of South America and its most recent significant earthquakes. http://wwwnei c.cr.usgs.gov/neis/current/s_america.html Notice how there are some earthquakes that happen nowhere near the plate boundaries (yellow lines). Small quakes can and do happen all over the place because the earth is still shifting and changing. Small quakes can be caused by something so small as an underground limestone cave collapsing to a something so grand as a new fault forming. Because the Earth is spinning in space, the fluid insides move around too. In some places, the crust or plates are a little thin, and molten rock comes out as a volcano. Volcanoes and earthquakes often go hand-in- hand. Another place to look is right next door, in the MadSci library (under Earth Sciences), there's a link to this page: http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html the title in the library is "plate tectonics and seismic waves" All of these sites combined can tell you much more than I can in only a few words. Good luck, and happy hunting!
Try the links in the MadSci Library for more information on Earth Sciences.