On Earth, these overlap when we deal with things like volcanoes. One can measure inflation and deflation episodes related to subsurface magma chambers, and of course, the visible surface products of eruptions and dislocation by faults.

IF Mars were geologically active, then we might search for such evidence to quantify HOW active it is. I doubt that MOLA had the resolution or the mission endurance to answer inflation/deflation questions but I may be wrong. Anyway, it's irrelevant - for Mars we take a different approach.

The simplest way to measure activity on Mars is to look for disturbances of original level surfaces by tectonic and volcanic processes, and to compare this to the accumulating "clock" of impacts. IF Mars is active, even very slowly, then there will be:-

1) Fresh, uncratered lava surfaces
2) Fresh faults in original smooth lava plains
3) tilting and changes of level in original flat/smooth lava plains

The sensitivity of this observation is MANY orders of magnitude finer than mere human time-scale tilts and swells.

Unfortunately we see very little of any of these features on Mars. The youngest volcanism appears to be many tens of thousands to a few million years old.

This does NOT mean that Mars is "dead" volcanically. Merely that there are long intervals between the brief episodes of activity for each volcano. This fits with the observation that none of the (probably independent) volcanoes on Mars shows any sign of current activity. (no hotspots, no really fresh lavas, no outgassing, no fumaroles, no recent mineralisation, no fresh fluid indicators)

On a timescale of a few million years, I fully expect some of the volcanoes of Mars to erupt again. A future observer will gain useful insight into the planet at this point. I hugely doubt than anyone now alive will still be around to see that moment, though.

In answer to another question - seismometers on Mars

The Viking missions did carry seismometers, but they were not favourably mounted. One failed on or soon after landing. The other seems to have recorded mostly wind vibrating the lander, rather than any earth movements.

Studies of tectonism on Mars indicate that there should be a healthy population of small earthquakes to measure (even the MOON has a few, that were well-detailed by the later Apollo missions)

Attempts to land a more modern seismometer have all failed, either due to failure to select the instrument for a mission, failure of the mission to fly, or failure to safely land.

Personally, I'd like to land a seismometer in Sysiphi Cavi to record the landslides/flows that appear to occur there every spring. Knowing the exact timing, duration, and seismic nature of the flows will help to understand what fluids are causing them.