$re = '/[:]\s(\".*\")/';
$str = '"ElevationFilenameIn": "Input raster elevation file",
"TargetCRS": "Target vertical coordinate reference system Type",
"TargetCRScode": "Target vertical coordinate system Code",
"TargetCRSfile": "The projection (.prj) file in shoebox to be used for this inputfile"';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php