My analysis is that the crack started at the insert and progressed outward to the side wall. If you flex the board do the top laminates separate from the sidewall ( open up downward in you picture) if so I would say never trust the board to be the only one you take with you . Your new rock board or the best excuse you can have to get a new board ! Pass it on to someone lighter to get started in the sport. As for how it happened only your bathroom scales knows for sure .