Lower white arrows in this image of Mercury’s surface show small fault scarps, indicating the planet is still tectonically active. Upper white arrows in the inset show small troughs that were likely formed due to the bending of the planet’s crust as it was uplifted. Image Credit: NASA/JHUAPL/Carnegie Institution of Washington/Smithsonian Institution
Mercury is a tectonically active planet that is likely forming new faults even today, according to a new study using data from NASA’s MESSENGER spacecraft.
Evidence was revealed in images captured by MESSENGER during its final 18 months orbiting the planet, which showed small fault scarps on the surface.
Fault scarps are ridges or cliff-like landforms that form when one side of a fault moves vertically in relation to the other side.
Larger, older fault scarps are already known to exist on Mercury, possibly caused by the planet’s contraction as it cooled over time.
But these newly discovered scarps are much smaller and measure just a few kilometres in length and tens of metres in relief.
Scarps of this size would be relatively quickly destroyed by meteor bombardment, indicating they must have formed quite recently.
This means Mercury can be grouped with Earth as another tectonically active planet in the Solar System.
“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet in our Solar System, with new faults likely forming today as Mercury’s interior continues to cool,” says lead author Thomas R. Watters of the Center for Earth and Planetary Studies at the National Air and Space Museum.