New research has revealed that the record-breaking massive earthquake that shook Mars in May this year was at least five times larger than the previous record.
It is not clear what the source of the quake was, but it sure was strange. In addition to being the strongest earthquake ever recorded on Mars, it was also the longest by several, shaking the Red Planet for about 10 hours.
“The energy released by this single quagmire is equivalent to the cumulative energy of all the other earthquakes we have seen so far,” says seismologist John Clinton of the Swiss Federal Institute of Technology in Switzerland. The intensity recorded in InSight is so great that it has nearly saturated our seismometer.” The new analysis of the quake, published in Geophysical Research Letters, pegged its intensity at 4.7. The previous record was held by a magnitude 4.2 detected in August 2021.
This may not seem like a large earthquake by Earth’s standards, as the strongest earthquake on record measured about 9.5 magnitude. But that for a planet thought to be seismically inactive until NASA’s InSight probe began recording its interior in early 2019 is surprising.
While Mars and Earth have a lot in common, there are some really important differences. Mars has no tectonic plates; It also doesn’t have a coherent global magnetic field, which is often interpreted as a sign that not much is going on inside Mars, where Earth’s magnetic field is supposedly caused by internal convection.
InSight has revealed that Mars is not as seismically calm as previously thought. It is shaking, alluding to the volcanic activity beneath the Cerberus Fossae region where the InSight probe is located, peering into the hidden bowels of the planet.
But determining the state of activity inside Mars isn’t the only reason to monitor earthquakes. The way seismic waves propagate across the planet’s surface could help reveal changes in density within it. In other words, they can be used to trace the structure of the planet.
“For the first time, we were able to identify surface waves, which move along the crust and upper mantle, and which have circled the planet many times,” Clinton says.
In two other separate Geophysical Research Letters papers, teams of scientists have analyzed these waves to try to understand the structure of the crust on Mars and to identify areas of sedimentary rock and possible volcanic activity within the crust.
But there is still a long way to go about the earthquake itself. First, it originated near, but not from, Cerberus Fossae, and we can’t trace it to any obvious surface features.
Earthquakes usually have a high or low frequency, the former characterized by quick and short tremors and the latter by longer and deeper waves of greater amplitude. This earthquake combined these two frequency bands, and researchers aren’t entirely sure why.
However, it is possible that high and low frequency earthquakes previously recorded and analyzed separately could be part of the same seismic event.
That could mean scientists need to rethink how they understand and analyze swamps, and discover more secrets lurking beneath Mars’ deceptively placid surface.
