Como mover um marcador 100 metros com coordenadas

$radius = 6378100; // radius of earth in meters
$latDist = $lat - $lat2;
$lngDist = $lng - $lng2;
$latDistRad = deg2rad($latDist);
$lngDistRad = deg2rad($lngDist);
$sinLatD = sin($latDistRad);
$sinLngD = sin($lngDistRad);
$cosLat1 = cos(deg2rad($lat));
$cosLat2 = cos(deg2rad($lat2));
$a = ($sinLatD/2)*($sinLatD/2) + $cosLat1*$cosLat2*($sinLngD/2)*($sinLngD/2);
if($a<0) $a = -1*$a;
$c = 2*atan2(sqrt($a), sqrt(1-$a));
$distance = $radius*$c;

$lat = 51.26667;        //  Just South of Aardenburg in Belgium
$lng = 3.45417;
$lat2 = 51.575001;      //  To the East of Breda in Holland
$lng2 = 4.83889;

$newLat = $lat + (($lat2 - $lat) * $ratio);
$newLng = $lng + (($lng2 - $lng) * $ratio);