I was reading about Supervolcanoes. This is just a term for really big volcanoes and was coined by the producers of the BBC program Horizon. And they mean so big that we do not recognise them as volcanos. When they erupt they do not form mountains of solid magma, but huge depressions where the land at the eruption site collapses. One of the largest super volcanoes in the world is in the US at the Yellowstone National Park. Geologists had observed that many of the rocks in the area were made of compacted ash, but they could find no extinct volcano or crater. It was only after NASA took some photos from the air of Yellowstone that the geologists were able to observe a massive caldera more than 2000 square kilometers wide. After analyzing the layers of ash, they determined that it had exploded 3 times in the last 2 million years. Each time was regularly spaced about 600,000 years apart. Just in case you are wondering, the last explosion was about 600,000 years ago. There are several other supervolcanoes in the world, notable among them Lake Toba in Sumatra and Kikai Caldera in Japan. What would happen if such a volcano exploded?
Disaster on a global scale. The supervolcano at Lake Toba exploded about 74,000 years ago and spewed out nearly 3,000 cubic kilometers of material, caused complete deforestation in South East Asia and triggered a volcanic winter that started an instant Ice Age. It also probably caused drastic population reduction worldwide. This explosive force would be about 10,000 times as violent as the Mt. St. Helens Eruption. If Yellowstone erupts it would probably cause death and destruction for hundreds of miles around it and also cover all of the United States with a layer of 2 meters of ash causing crops to vanish overnight. Who knows what the resulting volcanic winter will bring? but you can be sure that it will affect the whole world. It is really very humbling to realize how vulnerable mankind is to natural disasters.