NATURALDISASTER---EARTHQUAKETherearemanynaturaldisastersintheworld
Earthquakesareoneofthemostdangerous,overamillionearthquakesoccurseachyear
Althoughsomearetoosmalltobenoticed,othersmaycausedamages,deathanddestruction
EarthquakesarecausedbythemovementoftheEarth'scrust
Thecrustismadeupofplatesfloatingonmantle
Whentwoplatespushagainsteachother,itcausesearthquakeswhichmaydestroystownsorformnewclimates
Ifanearthquakehappensundertheseaandcauseshugewaves,itiscalleda"tsunami"
Atsunamicansweepacrossoceansatthespeedof800kilometersperhour
Whenanearthquakehappensoutintheopenseas,thewavecanonlybeabout1meterhigh,butwhenitmeetsland,itmaygrowupto30metershighandcanleadtoenormousdamage
Forinstance,aharboronOkushiriIsland,Japan,wasdestroyedbyatsunamiin1993
Whenanearthquakehappensonland,itmaycausemoredamaget