system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't we see any current volcanic activity on Mars?

I understand that Mars has had volcanic activity in the past. Why don't we currently see volcanoes erupting or lava flowing from time to time now?
gpt
Mars' volcanic activity is very different to that on Earth. Earth volcanism is driven by plate tectonics, with the vast, vast majority of volcanoes being located at either constructive or destructive plate margins. In contrast, volcanism on Mars is believed to be far more analogous to hot spot volcanism (that which forms the hawaiian islands for example).  Mars has no active plate tectonics due to the fact it's cooled down. That same explanation is highly likely to explain why Martian volcanism has died down.

Martian volcanoes are basaltic in nature - the same as plume volcanoes here on earth. That suggests they are forming from a partial melt within the mantle, then rising buoyantly through the crust. because Mars never had the active tectonics on a scale similar to Earth the crust has never been able to get highly silicious, hence crustal contamination of melt as it rises has not seemingly varied the chemistry too much from the original basalt.

It's possible Mars is still volcanically active, we're just in a window where we have not observed any eruptions. It may be that the eruption rate has died down significantly such that thousands or even millions of years may pass between events.

One interesting thing to note - because of the low atmospheric pressure on Mars, it means that while the chemistry of the basalts is fairly similar, instead of flowing out leisurely as they do on earth it becomes possible for gas bubbles to inflate to many times what you would expect in a heavier atmosphere. That drives the ascending jet more powerfully, which in turn means you can get far more violent eruptions from what on earth would behave as a fairly low-energy effusive eruption.