That is interesting. Especially since a FReeper just said he heard something analogous in the Dallas area.
I used to listen to ultra low frequency radio and heard a lot of different clicks, chirps and growns that are generally associated with ‘earth’ sounds.
Some of these sounds are almost identical, but I’ve never heard any without the help of a receiver. Especially this loud.
Could be the earth is starting to ‘yell’ instead of ‘whispering’ to get peoples attention.