Mars may not have tectonic plates like Earth, but that does not mean that the red planet is not capable of some serious earthquakes, with NASA’s InSight probe registering two more in what is believed to be an access point for seismic activity. The so-called “Marsquakes” are the last to be seen in Cerberus Fossae, a place that is no stranger to events that shake the soil.
NASA first discussed earthquakes in early 2020, having recorded magnitude 3.6 and 3.5 activity with the InSight seismometer. This instrument, known as the Sismic Experiment for Interior Structure (SEIS), is highly sensitive, which in itself has caused some problems.
InSight has a dome cover for SEIS, designed to prevent it from being affected by wind and other environmental causes of vibration that do not come from seismic activity. However, even that is not infallible, and during the Martian winter, there was enough wind on the red planet to effectively drown out any more nuanced readings. As a result, InSight was unable to detect earthquakes.
The tremors on Mars can be recorded on instruments like seismometers like those on Earth, but their cause is actually quite different. On our planet, changes in tectonic plates – which float on a layer of magma and then rub against each other – lead to earthquakes. Mars, however, has no plates, but it does have regions of volcanic activity that are capable of producing their own earthquakes.
Although InSight recorded evidence for more than 500 of these events during its time on Mars, these four are distinct among the data. They are the clearest that NASA has, with the new results of magnitude 3.3 and 3.1 giving weight to the theories that Cerberus Fossae is a hot spot for seismic activity on the planet. They also help to uncover details about how these earthquakes are similar and different from those with which we are most familiar.
“Throughout the mission, we saw two different types of marsquakes,” Taichi Kawamura of the Institut de Physique du Globe de Paris de France, in charge of SEIS, said of the new discoveries, “one that is more ‘Moon-like’ and the other , more ‘Earth-like’. ”The four clear readings are more like Earth, say the scientists.
The wind is not the only enemy of InSight when it comes to recording Marsquakes. The SEIS cabling itself can be a source of distortion, it seems, with the mooring cable connecting the instrument to the probe expanding and contracting as the temperature of Mars oscillates dramatically throughout the day and night. This, it has been theorized, is causing popping sounds and even spikes in the data.
To try to minimize it, InSight has used its robotic arm to drain dirt on top of the SIX dome. It is a temporary measure, in the hope that the Martian dirt will better insulate the cable. Then tho