<input onClick=shake(40) type=button value="Terremoto"Terremoto name="button""">
<script language=JavaScript1.2>
function shake(n) {
if (n==1)
{document.body.bgColor = "#0000DA";
}
else
{document.body.bgColor = "#FFFFFF"
}

if (self.moveBy) {
for (i = 15; i > 0; i--) {
for (j = n; j > 0; j--) {
self.moveBy(0,i);
self.moveBy(i,0);
self.moveBy(0,-i);
self.moveBy(-i,0);
}
}
}
}
</script>