function earthquake1() {
        for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,-2);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,+2);    //shake window left
        }

        window.moveTo(-4,-4);     //move window back to top corner
    }

    function earthquake2() {
        for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,5);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-5);    //shake window left
        }

        window.moveTo(-4,-4);     //move window back to top corner
    }

    function earthquake3() {
        for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,7);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-7);    //shake window left
        }

        window.moveTo(-4,-4);     //move window back to top corner
    }


    function earthquake4() {
	for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,10);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-10);    //shake window left
        }

        window.moveTo(-4,-4);
            //move window back to top corner
    }

    function earthquake5() {
	for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,14);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-14);    //shake window left
        }

        window.moveTo(-4,-4);
             //move window back to top corner
    }

    function earthquake6() {
	for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,18);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-18);    //shake window left
        }

        window.moveTo(-4,-4);
             //move window back to top corner
    }

    function earthquake7() {
	for (ctr=1; ctr <100; ctr++) {
            if (ctr % 4 == 0)
                window.moveBy(0,25);     //shake window right
            if (ctr % 4 == 2)
                window.moveBy(0,-25);    //shake window left
        }

        window.moveTo(-4,-4);
             //move window back to top corner
    }