Because Earth's last supervolcano erupted more than 70,000 years ago, scientists studying the phenomenon rely largely on studying geological evidence of past eruptions, or monitoring seismic and other activity underground.
But they do have another option: looking to Jupiter.
More specifically, looking to Jupiter's moon, Io, the most volcanic place in the solar system.
Chief volcano of Io's fiery fiefdom is a Connecticut-sized volcano called Loki. When scientists got a fresh look at Loki with the Galileo spacecraft on Thanksgiving Day 2002, they found a 125-mile-wide crater brimming with molten material, a lava expanse as wide as Lake Michigan.
"That one volcano is putting out as much heat as the entire planet Earth," said planetary astronomer John Spencer of the Southwest Research Institute.
Galileo's imager also caught many other volcanoes, including another monstrous eruption whose heat overwhelmed the instrument's sensor. It was dubbed Tvashtar, with a mile-high curtain of 1,800-degree-F lava gushing out of a 15-mile fissure down its center.
Volcanologists studying the science of "super eruptions" can learn a lot from Io, says Spencer. He explains that the ongoing eruptions on Io are somewhat like "super volcano" eruptions that have happened in Earth's past — like the 15 million-year-old Columbia River Flood Basalts in the Pacific Northwest, or the more recent (640,000-year-old) Yellowstone eruptions — only more extreme.
The reason for Io's endless eruptions is simple: Jupiter and the other jovian satellites won't let it rest. Io orbits closest to Jupiter and feels the tug of the outer satellites as well. Their vying gravities are constantly kneading the moon-sized world with tidal forces, keeping its innards roiling and hot.
"Humans have never witnessed Columbia River Basalts or Yellowstone eruptions," said Spencer. "Io has them frequently, so we can see them."
