tsunami is usually causd by strong arthquaks that happn in ocans.grat sa wavs will b pushd towards th shors with grat spd.if th popl along th shors don't know tsunami is coming,thy will suffr grat damag.for xampl,th tusnami,which happnd in th indian ocan on dcmbr 26,2004,killd mor than 150,000 popl in indonsia,sir lanka,india,thailand and othr countris.millions of popl wr injurd and bcam homlss.tsunami is a natural disastr.w should st up mor advancd warning systms along th shors,on th islands and in man-mad stallits.bsids,w should protct our ocans furthr instad of dstroying thm.