Marsquakes

You are very familiar with earthquakes.  Well, welcome to marsquakes.  Scientists used to believe that Mars died billions of years ago, along with any potential for activity, including seismic activity, deep within its core.  However, they are not so sure anymore.

“It’s likely that there may be marsquakes today, but seismic monitoring will be required to know for sure,” said marsquake study leader David Ferrill of the Southwest Research Institute in San Antonio, Texas. “Until then, it’s just scientific speculation.”   He continued, “With NASA striving to take humans back to the Moon and onto Mars and beyond, understanding the geologic activity of the planet can aid in future mission planning.”

Ferrill, who has an office at the University of Texas, examined images from satellites orbiting Mars which show strings of depressions lined up in a row.  Scientists wondered if the pit chains were either collapsed lava tubes or sinkholes carved by early water flows.  But they resembled pit chains in Iceland that formed along a fault based on seismic activity.  Scientists asked if these pits on Mars also could be created by seismic activity.

Using the terrestrial observations, along with lab work and mathematical modeling that took into account the different gravity of the two planets, Ferrill’s team found that the pit chains in Iceland and on Mars were likely formed by the same process.

“The general shape of faults is similar on both planets, however the lower Martian gravity produces steeper fault segments that extend down deeper into the crust than they do on Earth,” he said. “This allows for a larger void space near the surface into which loose surface material can collapse.”

Earth has plate tectonics as multiple plates scattered around the world move like glaciers, but over millions of years create significant seismic activity on earth.  Mars, which may have only one plate covering the planet and which is about 30 miles deep, does not have the same mechanism available for volcanic activity, but scientists are starting to wonder if Mars has tectonic activity that differs from earth’s.

“Although tectonically different from Earth, we see extensive evidence of faulting on Mars,” Ferrill said. “That means that when the planet was more tectonically active, faulting could have produced marsquakes similar to the earthquakes here on Earth.”

According to recent studies, Mars does have a core that is mostly iron and is partly molten.  This suggests that the red planet has not fully cooled following its formation about 4.5 billion years ago.  Even though volcanoes on the red planet appear to be dormant, scientists are not certain anymore.

Theorists expect the gradual cooling of Mars would have slowed tectonic activity over the past 3.5 billion years. Yet some think there could still be dozens of temblors a year with a magnitude of 3.5 or greater.  The cooling could cause contraction of the crust, which could cause seismic events at the surface.

“Because Mars is similar to the earth and the moon, both of which have seismic events, it is likely that Mars experiences marsquakes as well,” Ferrill said.