# Where do hydrothermal vents form inside icy ocean worlds?

Context: In a near-future version of our solar system, humans have established multiple underwater colonies on Jupiter's moon Europa. Many of these outposts are situated next to hydrothermal vents along the moon's rocky mantle. I want to place colonies next to vents as I make the world map, but I don't what pattern to place the vents in.

Given info:

• Europa likely has hydrothermal vents produced by tidal heating. Assume it does.
• Hydrothermal vents on Earth are located near plate boundaries.
• Europa probably has plate tectonics in its icy crust, but it's unclear whether it has tectonics in its rocky mantle. Therefore, it's unclear if there are vent-forming boundaries in the ocean or not.
• Since this moon has lower gravity than Earth, warm water is less buoyant. I'm thinking this may lead to more total vents, but each one may be less hot. If this is incorrect, feel free to challenge this assumption in the comments or answers.

Questions:

1. Could Europa have mantle plate tectonics that allow for boundary-adjacent hydrothermal vents?
2. If tectonics can't be present, would vents be clustered beneath the moon's tidal bulges, where tidal flexing is greatest?
3. Finally if not, would vents form at random "hot spots" above convection zones?

Tl;DR In order to place my underwater colonies correctly, where would hydrothermal vents form on a tidally-heated, icy moon such as Europa?

This is the same world as Generating breathable air on Europa and How big can Europan fish get?

• On Earth, hydrothermal ocean vents tend to be deep fissures in the crust where it is the thinnest/weakest and most susceptible to bending forces. Europa's forces are different, but would the results be? – StephenS Jan 27 at 5:16
• @StephenS I agree that the basic physics behind Europa's vents should work out the same, but that begs the question, "where is Europa's crust thinnest/weakest?" If not along plate boundaries, then where? – Zxyrra Jan 27 at 5:18
• I know that the massive gravity of Jupiter affects its moons a lot. Perhaps there's vents on the side facing jupiter, or maybe in a ring along that hemisphere? (obviously this is contingent on Europa being tidally locked, which I'm not sure of.) – Jakob Lovern Jan 30 at 1:46
• this answer might interest you earthscience.stackexchange.com/questions/4205/… – A. Soreq Jan 30 at 8:47
• Since Europa has a rocky mantle, not a magma mantle, and thus no tectonic plates, I believe it is impossible to have anything you could call "plate tectonics". The high tidal forces might cause any kind of cracks and movement in the ocean floor, but these would not follow the rules of tectonics. – cowlinator Feb 1 at 2:58

## Put them near the cracks

Tidal effects will happen to the rocky crust as well as the ice sheets above. We thus assume where we see venting and cracks on the icy cap, similar activity is happening directly below it.

Given this as the fundamental question: I want to place colonies next to vents as I make the world map, but I don't what pattern to place the vents in whether Europa has tectonics or not is irrelevant. We just care where and in what pattern it is warm/hot.

Voyager Map of Europa

Water Vapor Emissions

Based on this article about transient water vapor on Europa, it looks like most of the vapor is coming from near the south pole. Based on the Voyager map, we see a lot of cracks near the south pole.

If I were placing colonies under the ice, I'd position them near the cracks.

Be aware that these colonies may have to contend with periods of no thermal activity or that new thermal activity will happen somewhere not close by. The AstroBiology article states that vents were transient, about 7 hours. Colonies may need the ability to move to new vents.

• Nice, this is a pretty straightforward answer. Do you have a sense of the length of active thermal periods? i.e. will colonies have to move once a day or once a year? – Zxyrra Feb 3 at 16:35
• It'll depend on how the colony is designed and it's requirements for whatever it gets from the thermal vent. If the vent is the primary heat source then move a lot. If it's for some resource used in industrial processes then maybe you don't need to move as often. It depends. – Green Feb 3 at 17:49