Earth is not the only place where quakes happen. They occur on the Moon and even the Red Planet. The first marsquake was detected last April and since then over 100 events have been recorded, with 21 strongly believed to be quakes (although the others might be too).

Now, the team behind the detections has given us the chance to listen to the tremors on the Red Planet. The sonification is sped-up and slightly processed to be audible to the human ear and represents two marsquakes. The first had a magnitude of 3.7 and took place on the 173^rd sol (Martian day) of the mission, which was May 22, 2019, on Earth. The second one had a magnitude of 3.3 and happened on sol 235, or July 25, 2019.

The quakes were recorded by NASA’s Insight mission thanks to an extraordinary instrument called SEIS, aka the Seismic Experiment for Interior Structure. SEIS was developed by the French Space Agency, the Centre National d'Études Spatiales, and partners with the specific goal of studying the shakes of Mars. Equipped with information about marsquakes, planetary scientists can begin to study what the inside of the Red Planet is like.

"It's been exciting, especially in the beginning, hearing the first vibrations from the lander," said Constantinos Charalambous, an InSight science team member at Imperial College London. "You're imagining what's really happening on Mars as InSight sits on the open landscape."

Marsquakes are different from their Earthly and lunar counterparts. On Earth, seismic waves move mostly unimpeded through the crust and last a few seconds. Whenever fractures happen on our planet, over time, water brings in new minerals to fill these cracks. On the Moon, the crust is fractured due to impacts and the waves are scattered with the quakes lasting for tens of minutes. The situation on Mars is somewhere in-between, with waves lasting for a minute or so.

SEIS is remarkably sensitive and for this reason, researchers have a tough time distinguishing between quakes and other events. It can pick up movements of the nearby lander, the tenuous wind of Mars, and even the mechanical changes of the device itself. The team has started calling these the “dinks and donks”, which happen when parts of the device expand and contract as the temperature changes during the day.