var intensite = 30;
var coefficient = 0.97;
var signe = 1;
var f;

function tremblement() {
f.moveBy(signe*intensite, 0);
signe *= -1;
intensite = coefficient*intensite;
if(intensite>1) {setTimeout("tremblement()", 30);}
}

function ouvrirpopup() {
config = "width=300, height=10,";
config += "toolbar=no, location=no, directories=no,";
config += "status=no, menubar=no, scrollbars=no, resizable=no";
f = window.open("admin/userfiles/runcity974.htm", "page", config);
f.moveTo(100,100);
f.focus();
intensite = 50;
tremblement();
}