SOURCE

<div class="ripple"></div>

.ripple {
    left: 100px;
    top: 100px;
    box-sizing: border-box;
    position: relative;
    width: 100px;
    height: 100px;
    background: #09c;
    border-radius: 50%;
}

.ripple:before {
    background: #09c;
    animation: ripple 2s ease-out infinite;
    border: solid 2px #09c;
    border-radius: 50%;
    bottom: 0;
    box-sizing: border-box;
    content: "";
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
}

.ripple:after {
    background: #09c;
    animation: ripple 2s 1s ease-out infinite;
    border: solid 2px #09c;
    border-radius: 50%;
    bottom: 0;
    box-sizing: border-box;
    content: "";
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
}

@keyframes ripple {
    0% {
        opacity: .25;
    }
    100% {
        opacity: 0;
        transform: scale(2);
    }
}