I also seem to think that something got stuck between the door. And then got yanked out either catching the tire or road and that was your explosion. Maybe not the seatbelt but something else.
Seems rather difficult to target right at the door jam bullseye without much damage externally.
There does look to be damage to the side skirt in the first picture
True. Though still seems unlikely something went up thru the small crack and into the interior.
Seems more likely now that something was pull down thru the door jam. Maybe something that got caught when closing the door. The door seal does look to be bent towards the outside showing something leaving the cabin?
I could maybe see that. Would make sense with the damage pattern going down towards the rear of the vehicle rather than a forward angle of attack like you’d expect if you hit something while heading towards it. Maybe something like a belt where the rear tire finally grabbed the dangling end and pulled a belt buckle through?
Guilty as charged
To my detriment usually 
I would also say seat belt but you can see the belt in the picture and it ‘looks ok’
More than likely something was left hanging out the door (such as a jump rope) and it got caught in the tire and spat out.
A dog seatbelt (long enough to get under the wheel) 
Or a leash. I hope there was no dog attached to it lol
I think there wouldn’t be a thread if there was a decapitated dog involved. Unless the OP is a criminal mastermind covering his tracks by creating a thread of “I don’t know what happened”, when they really just got rid of wife’s yuppy little shitzu
Lol. I thought op was going to update us all! So many questions and no answers…
OP, any updates?
It has been a week. OP, message me if you’d like to re-open and fill us in
Sorry all, been away for a while (clearly). Ok, sooooo… it took me forever and a day to figure out what it could possibly be… and one day at 4am when I was up with my newborn it finally hit me: it was the anchor latch from my toddlers car seat… now it wasnt anchored in because I didnt need it to be… let me do some more explaining: i had my toddlers carseat in the cargo area of my SUV so the wife can sit in the back with our newborn from the hospital - we were in the hospital for a few days but when we got back she did a big grocery order for me to get and I had to pick up something else that was in a giant box… so I moved the carseat back into the spot where my toddler would be sitting and i just buckled it in without the anchor latches bc my toddler wasnt going to be going anywhere anytime soon anyway… and because I was just in a rush I guess I didnt notice the 50 foot seatbelt (exaggerated, obviously, but its long af for no logical reason at all) the anchor latches that are attached to the carseat was apparently hanging out… but I was out and about all day doing x, y, z and nothing happened UNTIL after my very last stop and I was 3 minutes from my house 
. There’s also like a giant seatbelt buckle on the latch of the carseat anchor for whatever reason (thats definitely what did the most damage). Not sure what the seatbelt got caught on (guessing it couldve wrapped around my tire?), but thats what did it, 100%.
User error, caused by small-human fatigue syndrome
An unfortunate freak occurrence, but certainly way better than an explosion going off under the seat randomly.
Thank you for closing the loop! Would have driven me nuts to not know the end of the story. Sorry to add car repair to the list that comes with a newborn, but congratulations on the family addition 
