Looking at Earth's seismicity in the Southern hemisphere(nearly non-existent), and seeing the near absence of lighter(hotter) elevated land masses there, gives the impression that Earth is quiescent and stable in the South sector.
We see on Mars the far thicker elevated Southern hemisphere and we cannot imagine the South being active and in motion. Can the deep Southern hemisphere be a source of Marsquakes if the crust is more elevated, and either cooler or more active in formation at depth?
Observing the Martian Northern hemisphere we see most of the well ordered and previously active geology landforms mixed with a predominance of lower elevation water influenced basaltic fill which has accommodated the elevation lows with infilling to a remarkable surface level of notable spherical flatness.
The contradictions give an expectation that Marsquakes should have been active in the North in Early Mars, and that they should have been concentrated in the North.
The Earth based GRACE gravity satellite shows that areas of severe gravitation imbalance(differentials) are concentrated in a fluid field along patterned general shapes when averaged monthly. Much change occurs in the details of the patterns but recurring simple shapes are present and recurring in periods of months and years.
Some unusual shapes of strong differential occur only in a few years or greater separation of timing, and they match distinguished land-form features we consider essential to plate tectonics and geological standards of change.
Most all 5 and greater Reichter scale quakes occur along the portions of these severe differentials, with few other strong Earthquakes anywhere else on Earth upon years of watching.
To find in Mars a corollary in shapes and patterned geological landmarks, and to find them formerly active in the Northern hemisphere matching that which is now occurring on Earth, gives a basic question as to whether the Mars and Earth of the past were also active almost exclusively in the North, showing a gravity field pattern which would allow for the actions recorded there.
Figure 2 for this article shows the 'Earth-like' gravity field similar structure for Mars returned from early and less sensitive equipment a few years past.
The similarity of the two planets despite reversals of materials, is remarkable and inescapable.
I'll find better graphics support for the concepts.