A nuclear war? The danger according to many is real, but still nobody has decided to push the button. A killer asteroid? Word it was among the causes of at least one of the great nass extinctions, but the NASA keeps an eye on the most dangerous objects and for now there are no alarms. An alien invation? Never say never, but at the moment the war of the worlds remains a sci-fi novels more than a scientific forecast. To be true, according to many famous scientists like Michio Kaku, the biggest threat to life on Earth is still the same from several hundreds of million of years: the possible eruption of a supervolcano.

24 active supervolcanoes in the world

On Earth there are 24 supervolcanoes, i.e. volcanic calderas with diemeter of tens of kilometers, able to eject a mass greater than a square kilometer (corresponding to class 5 of the Volcanic Explosivity Index or Vei-5). Falls into this category the Vesuvius, but even the Mount St Helens which in 1980 produced a column of eruptive ashes 24 kilometers high, spreading its hashes in 11 states, causing 57 victims and nearly 3 billion dollars damages. Yet the Vesuvius or the Mount St Helens turn pale in front of the "maximum weights" of categories 6, 7 and 8 of Vei.

Eruptions able to alter the Earth climate

Among Vei-6 category volcanoes (able to eject over 10 square kilometers of lava and hashes) there are the Krakatoa and the Pinatubo, which in 1991 ejected about 10 square kilometers of lava and 20 million tons of hashes, reducing for the next three years by around half degree the average global temperature. Among those of Vei-7 category (able to produce 100 square kilometers of lava and hashes) the only one to have erupted in recent times is the Mount Tombra, in Indonesia, in 1815, causing the second most cold winter since 1400 and a practically nonexistent summer in 1816 in the whole northern hemisphere.

Michio Kaku: be careful with the Yellowstone's caldera

But the true killer of life on Earth could be a category Vei-8 supervolcano, able to eject over 1.000 square kilometers of lava and hashes. There are four supervolcanoes of this category: the La Garita caldera, in Colorado, the Toba, in Indonesia, the Taupo, in New Zeland and the Yellowstone's caldera, in Wyoming. This one, according to the American physicist Michio Kaku (famous all around the world for his appearances in many Discovery Channel's popular series), should it wake up from its sleep lasting from over 640 thousand years, it could wype America off the map and modify the world forever as we know it today.

Also the humanity will ending up like the dinosaurs?

Not only: the risk constituted by the eruption of a supervulcano is accordint to scientists from five to ten times greater than the one of a giant asteroid hit our planet, causing a new mass extinction as those already happened at least five times in Earth history (the last, 65 million years ago, brought to the disappearance of the dinosaurs). In the case of Yellowstone's caldera, as of all the other supervolcanoes above remembered, many signs point out that activity did not stop and one day could come back with extreme violence and there is unfortunately no way to foresee when a supervolcano will return to upset the life on the Earth. The only thing to do is to continue to monitor them and to try to keep as far away as possible at the first sign of trouble.