Thermal Vents on Earth
A volcanic eruption on Io. Filmed from Galileo Orbiter
Being in Jupiters orbit has a price. For Io, at its closest point to Jupiter in its orbit, the surace of Io is 200 miles higher than when it is orbitting at its furthest point. The constant accordian effect on the moons generates volcanic activity that would end life on earth. The other moons suffer similar fates. Apparently they cant map the surface of Io because it is constantly being re-shaped by all the lava. Not molten rock but sulpher volcanoes!!
When they were photgraphing Ganymede one of the shots had a strange lump on it, it looked almost like another moon rising behind Ganymede. It later turned out it was a volcanic explosion 300 miles high. So big it changed the profile of the moon in that photo. Crazy!!
So tell me there arnt volcanic thermal vents at the bottom on Europa? Eruptions that would have melted the ice, forming seas underneath. And what do what, heat, and chemicals equal? Hey Presto....Life.