Mars' Quake Reveals Thicker Crust Compared to Earth

Thanks to the strongest Marsquake ever observed, planetary scientists now know the thickness of the Martian crust.

In a paper to be published in Geophysical Research Letters, researchers report that the crust of Mars is typically between 42 and 56 kilometers thick, which is about 70% thicker than Earth's average continental crust.

The data used for this measurement came from NASA's InSight lander, which recorded seismic waves from the quake that circled Mars up to three times. The measurement was made possible by a magnitude 4.7 quake that lasted more than six hours, which occurred last May.

The team also found that the thickness of the Martian crust varies across the planet, which may explain the known north-south elevation difference on Mars. Topological and gravity data from Mars orbiters suggested that the northern hemisphere of the planet is lower than the southern one because the rocks that make up northern Mars have a different density than those of southern Mars. However, the crust is actually thinner in the northern hemisphere, indicating that the rocks in both hemispheres probably have the same average densities.

By knowing the thickness of the crust, the team was also able to determine that much of Mars’ internal heat probably originates in the crust. According to computer simulations, an estimated 50 to 70 percent of the radioactive elements such as potassium, uranium, and thorium, which produce most of this heat, are in the crust instead of the underlying mantle. This suggests that some parts of Mars still have volcanic activity, contrary to a long-held belief that the planet is dead.

At Science News, it is our mission to provide accurate and engaging news of science to the public. As a nonprofit news organization, we rely on your support to keep our content free and accessible to the next generation of scientists and engineers. Invest in quality science journalism today by donating to our cause.