Tectonically Speaking

It Looks Like Mars Has Plates!

Remember back in geology class when we all learned about plate tectonics on Earth?  The continents and oceans of our planet ride along on crustal plates that jostle against each other like huge cracked regions in an eggshell, and in some places, dive under each other toward the mantle of our planet.  Those motions set off earthquakes, which you’ve probably heard about along such places as the San Andreas Fault in California.

Well, for the longest time, geologists and planetary scientists figured that Earth was the only planet we know about with plates.  Except now it turns out that Mars has a very primitive form of plate tectonics that are likely responsible for the formation of the huge Valles Marineris canyon system on the Red Planet.  UCLA scientist An Yin has discovered these plates by analyzing satellite images from the  THEMIS (Thermal Emission Imaging System), an instrument on board the Mars Odyssey spacecraft, and from the HIRISE (High Resolution Imaging Science Experiment) camera on the Mars Reconnaissance Orbiter.

Dr. Yin compared what has been found on Mars with studies done in the Himalayas and in California. There are striking similarities between the fault systems seen in these regions on Earth with canyons on Mars, which has a linear volcanic zone typical of plate tectonics.

In particular, the Valles Marineris region on Mars now appears to be an obvious product of plate tectonics, rather than just a crack opening up on the surface of the planet as scientists once thought. Yin suspects that this famous canyon system on the Red Planet is really a plate boundary that experiences horizontal motion. That’s similar to the motion along Earth’s San Andreas Fault, which periodically causes earthquakes.  The two plates divided by the Valles Marineris have moved approximately 93 miles horizontally relative to each other, according to Yin. By comparison, the San Andreas has moved about  twice as much, and the motions are comparable in type.

On Earth, the huge powerhouse of our core and mantle provide energy to move the plates around actively. Mars, on the other hand, doesn’t have as much activity at its core, which means that it likely has fewer plates and motions than Earth does.  This primitive state of Red Planet plate tectonics also means that Mars has quakes, just not as often as Earth does.

These days, Mars exploration is all the rage again, with the daily news and views from Curiosity, Opportunity, and the orbiters at the Red Planet sending back a constant flow of images and data. Discoveries of things like Martian plate tectonics are a natural outcome of all this Mars exploration. Not all discoveries get made overnight. Sometimes it takes years for scientists to get enough data and perspective to crystallize their findings. I’m excited to find out just what else we’re going to learn about Mars now and on into the future!

Speaking of exploring Mars, there’s a nifty 3D exploration of Mars that you can do right at your computer. Check out this view from Mars Day 2 from Curiosity.  I just spent some time playing with it, and I feel like I’ve just come back from a little Red Planet field trip.