Add ALT and TITLE tags to your Gravatars in WordPress for SEO and image tagging compliance.
Source: ALT & TITLE tags for Gravatars in WordPress – WireFlare
/*Añadir etiqueta alt a los avatares de Gravatar*/
function eg_gravatar_alt($text){
$alt = get_the_author_meta( 'display_name' );
$text = str_replace('alt=''', 'alt='Avatar de '.$alt.'' title='Gravatar de '.$alt.''',$text);
return $text;
}
add_filter('get_avatar','eg_gravatar_alt');