#marsquakes

One of the fractures making up the Cerberus Fossae system on Mars. The fractures cut through hills and craters, indicating their relative youth. Credit: ESA/DLR/FU Berlin (CC BY-SA 3.0 IGO)

Volcanic Activity on Mars Upends Red Planet Assumptions - Scientific American

For decades, planetary scientists assumed Mars was dead.

Geologically, that is. Smaller than Earth, the planet would have cooled faster than ours after it formed. It was, for a time, quite volcanically active. However, as the thinking goes, when the interior temperature gradually dropped, so too did the planet’s ability to generate large-scale geologic activity—such as huge volcanoes and marsquakes.

Recent discoveries, however, belie that belief. It just so happens that Mars is only mostly dead; scientists have found that a large region on Mars has been prone to quakes and even mild volcanic activity in recent geologic times, indicating something is brewing beneath the surface. But what?

Looking over data from several robotic Mars missions, a team of planetary scientists has come to the astonishing conclusion that an immense tower of hot material moving upward in the planet’s mantle is pushing on the crust from beneath, creating pressure that is cracking the surface and causing tectonic activity. Called a mantle plume, it may be a relatively new feature in the interior of Mars, and one that has analogues on—or, rather, under—Earth. It may even have implications for extant life on Mars—or more accurately, underneath it. The work was published in Nature Astronomy.

Mars Is Rumbling With Mysterious Quakes We've Never Detected Before

It turns out that Mars is rumblier than we knew. New techniques have revealed previously undetected quakes beneath the Martian surface – and, scientists say, the best explanation so far is ongoing volcanic activity.

The evidence seems to be mounting that Mars is far from dead, but hosts, underneath its dusty, barren surface, an interior gurgling away with seismic activity.

"Knowing that the Martian mantle is still active is crucial to our understanding of how Mars evolved as a planet," says geophysicist Hrvoje Tkalčić of the Australian National University in Australia.  

"It can help us answer fundamental questions about the Solar System and the state of Mars' core, mantle, and the evolution of its currently-lacking magnetic field."

For a very long time, scientists believed that nothing much was going on inside Mars.

The planet has very little in the way of a magnetic field. Planetary magnetic fields are (usually) generated inside the planet, by something called a dynamo – a rotating, convecting, and electrically conducting fluid that converts kinetic energy into magnetic energy, spinning a magnetic field out into space.

Mars' lack of a magnetic field suggests a lack of activity. This is a big deal; in fact, a magnetic field can mean the difference between life and death. Here on Earth, the magnetic field protects us from cosmic radiation that might destroy life. On Mars, radiation levels are much higher, even though it is more distant from the Sun.

"All life on Earth is possible because of the Earth's magnetic field and its ability to shield us from cosmic radiation, so without a magnetic field life as we know it simply wouldn't be possible," Tkalčić explains.

But when NASA's InSight lander arrived in November 2018 and started listening for Mars' heartbeat, we learnt something really remarkable: Mars is rumbling. To date, InSight has detected hundreds of marsquakes – enough to give us a detailed map of the Martian interior.

Tkalčić and his colleague, geophysicist Weijia Sun of the Chinese Academy of Sciences, wanted to look for quakes that might have gone unnoticed in the InSight data. They used two unconventional techniques, only recently applied to geophysics, to hunt seismic events in the InSight data.