Link: Charon’s icy surface erupted from an underground ocean

[steorra]

Charon’s icy surface erupted from an underground ocean

So the more plausible explanation is that the underground ocean escaped overground, allowing an icy slush to flood out over Vulcan Planitia. This could have occurred through cryovolcanism, the ice version of normal volcanoes. But these weren’t violent, Krakatoa-style eruptions. Instead, they would have been a slow creep of material through cracks in Charon’s surface.

A slightly more dramatic version of this slow flood depends not on small cracks, but on large-scale rupturing of Charon’s upper layers. In this scenario, the surface doesn’t just crack, but founders into huge chunks which sink or tilt into the slushy ocean.

This would have probably caused a faster flooding, but the end result looks identical as far as New Horizons’ images can show.