A supervolcano is a rare extremely large volcano which has the potential to produce an eruption with major effects on the global climate and ecosystem. There are about 12 known supervolcanoes currently. If just one supervolcano erupted the surrounding area would be incinerated due to the lava and super-heated gas. However, what would really effect the whole globe would be a thick, black ash which would stretch for hundreds of miles and would act like a blanket smothering everywhere it reaches. An incalculable number of people would die, their lungs ripped open by the sharp ash particles. The temperature of the Earth would drop due to gases from the Earth combining with the atmosphere. The Yellowstone supervolcano alone would cover Idaho, Wyoming, Montana and additional other states.
Certain features of a supervolcano include being able to erupt at least 1,000 km3 of material, compared to a large volcano which would spew just 1 km3 of material. They also form a depression, known as a caldera so unlike a usual volcano which forms a cone shape, it forms a large cauldron-like hollow circle in the ground. They erupt a lot less often, roughly hundreds of thousands of years apart. Yellowstone has only been recorded to erupt 3 times in the last 3 million years. However, they are extremely powerful with Yellowstone’s last eruption (630,00 years ago) was around 1,000 times bigger than the Mount St Helens eruption in 1980 which killed 57 people and roughly 7,000 animals, the end result left hundreds of homes and miles of highway destroyed.