div background image
#avatar {
/* This image is 687 wide by 1024 tall, similar to your aspect ratio */
background-image: url('http://i.stack.imgur.com/Dj7eP.jpg');
/* make a square container */
width: 150px;
height: 150px;
/* fill the container, preserving aspect ratio, and cropping to fit */
background-size: cover;
/* center the image vertically and horizontally */
background-position: top center;
/* round the edges to a circle with border radius 1/2 container size */
border-radius: 50%;
}