Marsquakes could unveil underground water on Mars

If liquid water exists today on Mars, it may be too deep underground to detect with traditional methods used on Earth. However, listening to earthquakes that occur on Mars – or marsquakes – could offer a new tool in the search, according to a team led by Penn State scientists.

When quakes rumble and move through aquifers deep underground, they produce electromagnetic signals. The researchers reported in the journal JGR Planets how those signals, if also produced on Mars, could identify water miles under the surface. The study may lay the groundwork for future analyses of data from Mars missions, according to Nolan Roth, a doctoral candidate in the Department of Geosciences at Penn State and lead author.

“The scientific community has theories that Mars used to have oceans and that, over the course of its history, all that water went away,” Roth said. “But there is evidence that some water is trapped somewhere in the subsurface. We just haven’t been able to find it. The idea is, if we can find these electromagnetic signals, then we find water on Mars.”

If scientists want to find water on Earth, they can use tools like ground-penetrating radar to map the subsurface. But this technology is not effective miles under the surface, depths where water may be on Mars, the scientists said.

Instead, the researchers recommend a novel application of the seismoelectric method, a newer technique developed to non-invasively characterize Earth’s subsurface. When seismic waves from an earthquake move through an aquifer underground, differences in how rocks and water move produce electromagnetic fields. These signals, which can be heard by sensors on the surface, can reveal information about aquifer depth, volume, location and chemical compositions, according to the researchers.

Roth said future work will – surprisingly – involve analyzing data already collected on Mars. NASA’s Insight lander, launched in 2018, delivered a seismometer to Mars that has been listening to marsquakes and mapping the subsurface. But seismometers have difficulty distinguishing water from gas or less dense rock.

However, the mission also included a magnetometer as a diagnostic tool to help the seismometer. Combing data from the magnetometer and the seismometer could reveal seismoelectric signals, the scientists said. Sending a dedicated magnetometer meant to conduct scientific experiments on future NASA missions could potentially produce even better results, the researchers said.

“This shouldn’t be limited to Mars – the technique has potential, for example, to measure the thickness of icy oceans on a moon of Jupiter,” Zhu said. “The message we want to give the community is there is this promising physical phenomena – which received less attention in the past – that may have great potential for planetary geophysics.”

Yongxin Gao, professor at Hefei University of Technology in China, also contributed.