Many of them do. Not only comets and asteroids threaten humankind but apocalyptic solar storms in our own sun could end civilization as could a nearby star turning supernova. A major collision with black hole—such as the one at our galaxy’s core—could prove lethal for life on earth . . . particularly if that collision involved another black hole.
Some of humanity’s worst threats, however, come from the earth’s bowels, where many mythologies have believed hell resides. It turns out those mythologies were right. Supervolcanos—whose colossal calderas are measured in terms of square miles, sometimes tens of square miles—are scattered around the earth, and their explosive potential is earth-shattering. One supervolcano in Lake Toba, Indonesia detonated 74,000 years ago. Blanketing the earth in ash and flaming ember, it destroyed 90 percent of homo sapiens. The rest found themselves in a world of sunless blackened skies, the air choked with drifting volcanic debris. They must have truly thought they were in hell—and they were.
Most are under or near the sea, but one landlocked supervolcano is in America’s Yellowstone Park and is due to detonate every 600,000 years. The last time it blew was 640,000 years ago, so it’s 40,000 years overdue—and it’s making its impatience known. Groaning, sobbing, roaring, occasionally erupting, the pressure inside its magma chamber has increased dangerously during the last decade—to unprecedented levels. Eventually its chamber-roof will detonate, and the volcanic mountain will again blow apart with the force and velocity of a crashing asteroid and 100,000 thermonuclear bombs. Melting, demolishing and devouring the surrounding mountains, the explosion will expand its already massive cauldron-shaped volcanic crater, currently 34 by 45 miles. This vast depression is called “the Yellowstone Caldera”—or by tourists, “Yellowstone Park.”
The last time the Yellowstone supervolcano blew, it ejected 1,000 cubic kilometers of flaming hell into the atmosphere, which, coming down, buried North America in two meters of smoldering debris. That detonation had also effectively exterminated many of the world’s life forms and plunged the planet into black, volcanic winter . . .
-- Can we do anything to mitigate supervolcano disasters?
Some scientists believe sophisticated slant-drilling could syphon off the caldera’s pressure. Testing that thesis would require a lot of work, and money however. So far, we have no workable computer models.