It turns out that Mars is rumbling louder than we know. A new technique has revealed previously undetected earthquakes beneath the Martian surface. According to scientists, the best explanation so far is, it is due to ongoing volcanic activity.
It seems that there is growing evidence that Mars is not currently dead. Beneath its dusty and barren surface, the interior of Mars is "beating" with seismic activity.
"Knowing that Mars' mantle is still active is critical to our understanding of how Mars evolved as a planet," said geophysicist Hrvoje Tkalči of the Australian National University in Australia.
"This could help us answer fundamental questions about the Solar System and the state of Mars' core, mantle, and the evolution of its currently absent magnetic field."
For a very long time, scientists believed that not much was happening inside Mars. This planet has very little magnetic field. To note, planetary magnetic fields are (usually) generated inside planets by something called a rotating, convective, electrically conducting fluid dynamo that converts kinetic energy into magnetic energy. This energy spins a magnetic field out into space.
Mars' lack of magnetic field indicates a lack of activity. This is a big problem. In reality, a magnetic field can mean the difference between life and death. On Earth, magnetic fields protect us from cosmic radiation that might destroy life. On Mars, radiation levels are much higher, even though it is farther from the Sun.
"All life on Earth is possible because of Earth's magnetic field and its ability to protect us from cosmic radiation. So without the magnetic field of life as we know it, this would not be possible," explains Tkalči.
Mars Heartbeat
But when NASA's InSight lander arrived in November 2018 and began listening to Mars' heartbeat, we learned something quite extraordinary: Mars rumbles. To date, InSight has detected hundreds of Martian earthquakes. This information is enough to give us a detailed map of the interior of Mars.
Tkalčić and his colleague, geophysicist Weijia Sun of the Chinese Academy of Sciences, wanted to look for earthquakes that might have gone unnoticed in the InSight data. They used two unconventional techniques, recently applied to geophysics, to hunt down seismic events in InSight data.
Based on nine known patterns of martian earthquakes, both detected 47 new seismic events, originating in a region on Mars called the Cerberus Fossae, a system of cracks created by faults, such as those that have separated the Earth's crust.
Most of the new seismic events resemble the waveforms of the two infamous Cerberus Fossae earthquakes that occurred in May and July 2019, suggesting that the smaller quake is related to the larger one.
Then researchers find out the cause of the earthquake. Their analysis found that no pattern was found in the timing of the earthquakes, excluding causes such as the influence of the Martian moon Phobos.
"We found that these marsquakes occur repeatedly throughout the day on Mars, whereas the marsquakes detected and reported by NASA in the past appear to only occur at midnight when the planet is calmer," Tkalči said.
"We can therefore assume that the movement of molten rock in the Martian mantle was the trigger for the 47 newly detected Martian earthquakes beneath the Cerberus Fossae region," he said.
Previous analysis of features on the Martian surface at Cerberus Fossae found that the region had been volcanically active more recently, in the last 10 million years or so.
The activity identified by Sun and Tkalči, which is associated with the repetitive motion of magma in the Martian mantle, also suggests that Mars is more volcanically and seismically active than we thought. If this is the case, the results have implications for our understanding of Mars' history and future.
"Earthquakes indirectly help us understand whether convection occurs within the planet's interior, and if this convection occurs, which seems to be based on our findings, then there must be another mechanism at play that prevents magnetic fields from developing on Mars," Tkalči said. .
"Understanding Mars' magnetic field, how it evolved, and at what stage the planet's history stopped is clearly important for future missions and is critical if scientists one day hope to establish human life on Mars."