Watch FMovies. Earth is a volcanic planet, with over 1,400 active giants spread across the globe. But what would happen if all of them were to erupt at once? From rivers of lava, towering ash clouds, and pyroclastic flows to tsunamis and super-sized climate change, we explore the powerful volcanic forces that fascinate today's scientists. Join us as we conduct a thrilling thought experiment with leading volcanologists that reveals the inner workings of some of the world's most magnificent volcanoes.