How to create a pulse effect using -webkit-animation - outward rings

I have found this article:

http://www.zurb.com/article/221/css3-animation-will-rock-your-world on css3 animations.

I am trying to create a similar effect seen on the site above but on personal site at: www.imfrom.me

Where I have the state of Maine, there is the red tip box. I want to create a pulse ring by the arrow indicating the location.

UPDATED WITH CODE:

I came up with this below (try it here: http://jsfiddle.net/ftrJn/) as you can tell its close, any thoughts on how I can get it to grow from the center:

.gps_ring {
    border: 3px solid #999;
    -webkit-border-radius: 30px;
    height: 18px;
    width: 18px;
    position: absolute;
    left:20px;
    top:214px;
}
.gps_ring{
    -webkit-animation-name: pulsate;
    -webkit-animation-duration: 1s;
    -webkit-animation-timing-function: ease-in-out;
    -webkit-animation-iteration-count: infinite
}
@-webkit-keyframes pulsate {
    0% { width:1px;height: 1px; opacity: 0.0}
    10% { width:3px;height: 3px; opacity: .20}
    20% { width:5px;height: 5px; opacity: .40 }
    30% { width:7px;height: 7px; opacity: .60 }
    40% { width:9px;height: 9px; opacity: .80 } 
    50% { width:11px;height: 11px; opacity: 1.0}
    60% { width:13px;height: 13px; opacity: .80}
    70% { width:15px;height: 15px;  opacity: .60}
    80% { width:17px;height: 17px;  opacity: .40}
    90% { width:19px;height: 19px;  opacity: .20}
    100% { width:21px;height: 21px;  opacity: 0.0}
 }

Thoughts on that above?

Any ideas on how I can create something like that as if rings animate out and fade away?

Solution

You have a lot of unnecessary keyframes. Don't think of keyframes as individual frames, think of them as "steps" in your animation and the computer fills in the frames between the keyframes.

Here is a solution that cleans up a lot of code and makes the animation start from the center:

.gps_ring {
    border: 3px solid #999;
    -webkit-border-radius: 30px;
    height: 18px;
    width: 18px;
    position: absolute;
    left:20px;
    top:214px;
    -webkit-animation: pulsate 1s ease-out;
    -webkit-animation-iteration-count: infinite; 
    opacity: 0.0
}
@-webkit-keyframes pulsate {
    0% {-webkit-transform: scale(0.1, 0.1); opacity: 0.0;}
    50% {opacity: 1.0;}
    100% {-webkit-transform: scale(1.2, 1.2); opacity: 0.0;}
}

You can see it in action here: http://jsfiddle.net/Fy8vD/