Since no one wanted to explain it to you too well, I'll go ahead. Basically, no, it's not a realistic threat. The problem with your idea is that the biggest explosion that humans could possibly make, or even expect to make in 100 years, wouldn't have a fraction of the power needed to blow apart the moon.
Think about the comet impact that killed the dinosaurs. It was an explosion with a power far beyond what humans cam make today. Even that amazing amount of energy was only enough to carve a wide but shallow divot on the crust of the earth.
Also, to answer your question of what could happen if the moon did explode, the answer is simple: all life all earth would perish in a fiery then frigid apocalypse. Even a glancing blow of the moon by a good sized comet could, as far as I know, rain down explosive hell on the entire planet.