Even more mysterious is that some people reported hearing booms at other times during the day as well, ranging from 2 p.m. to 6 p.m. to 1 a.m. on Christmas morning.
That's what the news is reporting, but I think it was too widely felt for that. Even the news people can't wake the seismic people! There were way too many booms, and frost quakes are always single events.
The source of one frost quake was discovered in the northern US, and was a surface buckle of rock. That makes sense, it is what we call a pop-up. We all must try to wake up the seismic people, and especially the infra-sound people to get a full list of the events.
Update: Article Apparently, these ice quakes have hit in a great group before. Ice quakes would be locatable with the seismic network, if there were somebody to look at them. Perhaps we should all raise money on Kickstarter?