In light of what we know about geological activity on the terrestrial worlds, why might it seem surprising to find geological activity on jovian moons?

Because they are relatively small in size

Explanation:

Geological activity can be explained as the movement of irregularly shaped slab of solid rocks, known as tectonic plates beneath the surface of the earth. It has been discovered that , this geological activity is present because of heat.

In Jovian moons, it has been discovered that , geological activity is present not only because of the tidal heat, but also because of their shapes, i.e composition.

Some of the evidences of the geological activity which have been observed in the Jovian moons include

* Active volcanoes

* Ice crystals being sprayed out into space  

* Surfaces with very few impact craters.

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