On our own planet, magnitude 4.0 earthquakes are big enough to feel beneath your feet, but not big enough to inflict much damage. Still, InSight’s accomplishment is akin to landing a single car-sized probe in West Texas and having it detect a series of relatively small earthquakes out in Los Angeles.

“We’ve seen evidence for volcanic flows, faulting and fluvial flows — water on the surface — within the last 10 million years in (Cerberus Fossae),” says InSight Deputy Principal Investigator Sue Smrekar of NASA’s Jet Propulsion Laboratory. “Our quakes that we have been able to locate so far are in that area. It’s intriguing in that if you just took a simple model of the thermal evolution of Mars, we wouldn’t really expect such recent volcanism in that area."

As they learn more about the specific kind of geologic activity happening in Cerberus Fossae, it should also offer clues about the variability of volcanoes around Mars, she added.

The shaking didn’t stop there either. InSight ultimately felt a whopping 174 seismic events on Mars. The marsquakes fell into two distinct categories: 24 were large and far away from InSight, and the others were much smaller and had distinctly higher wavelengths, a sign they were propogating closer to the surface.

Piercing the Red Planet

So far, Mars’ seismic activity seems similar to what exists on Earth away from plate tectonic boundaries. And the importance of these marsquakes goes far beyond the gee-whiz factor of simply knowing that they exist.

Much of what geologists have learned about the interior of our own planet comes from seismic activity. As seismic waves travel through a world’s interior, their speed and direction change as they hit materials with different densities. So, with each signal sent back by NASA’s InSight lander, it’s letting scientists peek inside the Red Planet.