CSS: How do I create the Ken Burns effect (photo-zoom)?

This effect describes the slow zoom into a photo, which is often used with sliders to create a little more movement on an otherwise static web page.

This effect can also be recreated with some CSS:

<div class="image-wrap">
  <img src="link-to-the-image.jpg">
</div>

.image-wrap {
  width: 100%;
  height: 50vw;
  margin: 0 auto;
  overflow: hidden;
  position: relative;
}

.image-wrap img {
  width: 100%;
  animation: move 40s ease;
  -ms-animation: move 40s ease;
  -webkit-animation: move 40s ease;
  -0-animation: move 40s ease;
  -moz-animation: move 40s ease;
  position: absolute;
}

@-webkit-keyframes move {
  0% {
    -webkit-transform-origin: bottom left;
    -moz-transform-origin: bottom left;
    -ms-transform-origin: bottom left;
    -o-transform-origin: bottom left;
    transform-origin: bottom left;
    transform: scale(1.0);
    -ms-transform: scale(1.0);
    /* IE 9 */
    
    -webkit-transform: scale(1.0);
    /* Safari and Chrome */
    
    -o-transform: scale(1.0);
    /* Opera */
    
    -moz-transform: scale(1.0);
    /* Firefox */
  }
  100% {
    transform: scale(1.2);
    -ms-transform: scale(1.2);
    /* IE 9 */
    
    -webkit-transform: scale(1.2);
    /* Safari and Chrome */
    
    -o-transform: scale(1.2);
    /* Opera */
    
    -moz-transform: scale(1.2);
    /* Firefox */
  }
}