August 10, 2012
Mars Joins Earth As Only Planets Known To Have Plate Tectonics
Lawrence LeBlond for redOrbit.com - Your Universe Online
For decades, scientists thought the only place in our solar system that consisted of plate tectonics was right here on Earth. But a UCLA scientist has discovered, analyzing data from two instruments, that the Red Planet has also shown evidence of tectonic plate movement.
The science of plate tectonics revolves around the idea that huge crustal plates beneath a planet´s surface are constantly moving, rubbing and grinding against each other. These movements are the driving force of earthquakes, volcanic activity, and the building up of mountain ranges, among other things.
An Yin, the UCLA scientist who discovered the geological phenomena on Mars, said: “Mars is at a primitive stage of plate tectonics. It gives us a glimpse of how the early Earth may have looked and may help us understand how plate tectonics began on Earth.”
Yin, professor of Earth and space sciences at UCLA, discovered the phenomena through an analysis of satellite images taken from NASA´s THEMIS spacecraft and also from the HIRISE camera on NASA´s Mars Reconnaissance Orbiter (MRO). He said about a dozen of the 100-or-so images collected show signs of plate tectonics.
Yin has previously conducted plate tectonic research in the Himalayas and Tibet, where two of the Earth´s major plates divide. “When I studied the satellite images from Mars, many of the features looked very much like fault systems I have seen in the Himalayas and Tibet, and in California as well, including the geomorphology,” he said.
In one image, Yin observed a very smooth, flat side of a canyon wall, which can only be generated by a fault; a steep cliff also observed, much like the cliffs found in California´s Death Valley, is also typical of a fault line. Yin also said he found a linear volcanic zone on Mars, which is another formation of tectonic plate movement.
“You don't see these features anywhere else on other planets in our solar system, other than Earth and Mars,” said Yin, whose research is featured as the cover story in the August issue of the journal Lithosphere.
For the better part of the last half century, scientists had wondered how one of Mars´ largest canyon systems, Valles Marineris (Latin for Mariner Valleys), was formed. For a long time the standing theory was a huge crack opened up on the planet´s surface, resulting in the formation of the vast system of canyons and valleys. Yin said the nearly 2,500-mile-long canyon system was actually formed through plate tectonics.
“In the beginning, I did not expect plate tectonics, but the more I studied it, the more I realized Mars is so different from what other scientists anticipated,” Yin said. “I saw that the idea that it is just a big crack that opened up is incorrect. It is really a plate boundary, with horizontal motion. That is kind of shocking, but the evidence is quite clear.”
“The shell is broken and is moving horizontally over a long distance. It is very similar to the Earth's Dead Sea fault system, which has also opened up and is moving horizontally.”
Valles Marineris is divided by two plates that have moved roughly 93 miles horizontally relative to each other, Yin explained. That is similar to the San Andreas Fault in California. While the San Andreas fault has moved twice as much, the similarity can be made because Earth is also nearly twice as big as Mars, making the two situations comparable.
Unlike Earth, which has seven major plates, Mars has relatively few, according to Yin. He does believe that Mars could be on its way to becoming “very broken,” which would mean the formation of more plates; more plates would mean more Mars-quakes. For now, he added, quakes probably don´t happen very often. The plates wake up “every once in a while, over a very long duration -- perhaps every million years or more.”
While he is confident in his findings, Yin said there are still mysteries, including how far beneath the surface the plates are located. “I don't quite understand why the plates are moving with such a large magnitude or what the rate of movement is; maybe Mars has a different form of plate tectonics“¦ The rate is much slower than on Earth.”
Yin said he will continue to study plate tectonics on Mars and plans to publish a future update paper in the journal Lithosphere. His research has been partly funded by the National Space Foundation.