loud

This past winter I starting noticing a LOUD thudding noise that vibrates my whole house. At first it would only last 15 - 20 seconds. As it was seemingly coming from my basement where all the mechancial "guts" of my home are, my first guess was that it was my hot water heater vibrating from...

Every now and again (maybe once a month?) I hear a loud strong rumble that shakes the house a little. I even felt it while sitting out in my backyard once. Felt like a little earthquake! Not sure what it is or how to begin diagnosing it. Any ideas? We are on a well. Thanks!