I drew a line from the lower lip of Salma to the point of her chin (click on the image for larger view). You can see that the line is perpendicular to the floor plane with the lower lip slightly overlapping the superior lip. This is typical of strong chin-ed women and in our opinion it gives the profile of Salma a statuesque beautiful look.
I also measured, in green on the image, the distance between the nose base and the upper lip, and in yellow, from the lower lip to the point of the chin (click on the image for larger view). The nose base / upper lip = 0.66, while the lower lip / chin point = 2,17. It means that the chin distances = 3.28x more distance than the upper lip/nose distance. In other words, the chin accounts for 76% of Salma's lower face. Again, this is typical of strong chin-ed /square jawed women where the chin tends to advance and "eat" the lower face height against the upper lip. I also noticed, aside from chins, that the small upper lip height is a feminine characteristic.
Such a small upper lip to nose base distance, in contrast to a much larger lower lip to chin point distance is in our opinion a requisite for superior female beauty.
( More Salma Hayek pictures: http://www.womenlargejaw.com/taxonomy/term/30 )