[Boogieman]

I doubt it is impact related, since it seems to be happening in the same area with some regularity.

I also don’t think this could be an aurora though, because Mars has a very weak magnetosphere, and besides, auroras are upper atmosphere phenomena, while this seems to be directly in contact with the surface.

My best guess is some type of massive venting, possibly from ice near the polar caps sublimating. The most detailed photo does really look like the venting we see on some of Jupiter’s moons, with multiple venting sites located close together.

[SunkenCiv]

Thanks, but it doesn’t say that more than one event happened in the same place, only that two different amateur astronomers saw the same plume about 10 days apart, and that on other occasions in the past, different plumes were seen, which could easily mean that surface impacts happen on Mars, which has very thin atmosphere (surface pressure on Mars is about the same as 40 miles altitude above Earth).