There have been many unexplained explosions in central Texas also, usually between 3:30-4am but not all. Just search boom in Austin subreddit. Shills keep blaming it on fireworks and transformers, but OPs suggest its much louder than that and happening to often. East of Zilker was mentioned quite a few times. DUMB activity maybe?
Pls report back if any digs further into this. Saving this thread