I heard a tremendous rumbling in the NW suburbs of Chicago in the early hours of Tuesday, April 18th, 2017 at around 3 AM. It was a long, sustained rumbling, very deep, almost like the sound a massive garbage can would make if it was dragged across the ground. This was definitely not the standard engine noise from O’Hare: I hear airplane and construction sounds from there all the time (and have heard them for many years), and nothing was ever this loud. It practically shook the house, and it lasted for around half a minute or more.
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