A new study in Nature Geoscience reveals that Earth is not the only tectonically active planet in the solar system. Images taken by NASA’s Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft prove that Mercury still experiences earthquakes or Mercuryquakes.
It has been known that the planet contains massive fault scarps or cliffs. During MESSENGER’s final 18 months orbiting, it took images that reveal these cliffs can be longer than 1,000 kilometers and over three kilometers high.
These cliff-like landforms form when rocks get pushed together and upwards along faults in Mercury’s crust. Scientists believe that these indicate global contraction of Mercury as its interior cooled, shrinking the crust.
However, MESSENGER also took images that show that some of these landforms measure only less than 10 kilometers long and several dozens of feet tall. Experts believe that these fault scarps are less than 50 million years old.
According to the study’s lead author Thomas Watters, a planetary scientist at the Smithsonian Institution’s Center for Earth and Planetary Studies in Washington, this shows that Mercury is still rumbling with Mercuryquakes, which are produced by its cooling and shrinking.
“These small-scale thrust fault scarps are orders of magnitude smaller, only a few kilometers in length and tens of meters of relief, than larger scarps previously known to exist on the surface of Mercury,” points out the study’s co-author Maria Banks, a scientist from the Planetary Science Institute Research, who also helped analyze the images of these tiny tectonic structures. “Steady meteoroid bombardment quickly degrades and destroys structures this small, indicating that they must have formed relatively recently. They are comparable in size to very young fault scarps identified on the lunar surface attributed to shrinking of the Moon.”
If seismometers can be deployed on the planet during future missions, scientists could learn more about these Mercuryquakes.