Re: Underground "sonic booms" in Wisconsin
What caught my eye was the article said they had about twenty reports, which is similar to my relative's situation. It was neighborhood in scale. I did catch a glimpse of a map on the network news with locations of the calls, but have not been able to locate a copy of it. That's good information for locating the hypothesized cave collapse. GIS geek, as always.
Also, I'm of the opinion that collapses of caves in dry years is louder due to air-pressure waves in the dry caverns. Just a thought.