This phenomenon is never helped by the person who inevitably pipes up, "you know, statistics show an awkward silence occurs every seven minutes during conversation," or "you know, studies show people can only allow an awkward silence to occur for nine seconds before someone says something. There. I've said something."
So no one can surround himself with interesting people all the time - and interesting people are often the prevention to awkward silences - it is best to be armed with something in the back files of your mind to share in a group setting. Not gossip. Not depressing news. Not inane rambling about yourself. Not inflammatory topics. (I acknowledge that "inflammatory" is relative.) Rather, something, as etiquette experts of old encouraged, that the whole group might find interesting.
I hope you find yourself befriended by people who allow occasional deep silences to permeate the atmosphere - silences of companionship rather than anxiety.
For other times, perhaps some of these stories will come in handy. But I trust your silence is a comfortable one.