The strongest Mars quake to date lasted ten hours (but it’s unclear how it originated)

The puzzling Martian earthquake measured 4.7 on the Richter scale and lasted hours longer than any previously detected quake.

Late on Earth’s night on May 4, 2022, the seismometer aboard the Mars InSight lander detected a major earthquake on the Red Planet. It soon became clear that this Martian earthquake was far was the strongest alien earthquake ever detected. In a new study, researchers are now revealing the first data on this unprecedented and record-breaking event.

Learn more about Martian earthquake hunting
Why are scientists so interested in Martian earthquakes? Observing earthquakes on Mars is not an end in itself, but rather a way to better understand the red planet. Seismic waves pass through the crust, mantle and core of the Red Planet and undergo changes under the influence of the different layers inside Mars and the materials that compose them. By studying the waves and the changes they undergo, researchers can better understand the thickness and composition of these inner layers. This will hopefully give them a better idea of ​​what lies beneath the planet’s surface (like water) and how the crust and deep interior are made up. And that in turn gives better insight into the composition of Mars as a whole and how the Red Planet – but also other rocky worlds – formed.

Until recently, an earthquake that occurred in August 2021 and measured 4.2 on the Richter scale was the strongest earthquake of all time. But this former record holder is now largely dethroned.

The biggest quake on Mars
May’s earthquake had a magnitude of 4.7 on the Richter scale, making it no less than five times more intense. “It’s definitely the strongest Martian earthquake we’ve seen,” said researcher Taichi Kawamura. The energy that was released even appears to be equal to the energy of all previous Martian earthquakes added together. “Although the event occurred more than 2,000 kilometers from Insight, the waves recorded by the lander were so intense that our seismometer nearly overloaded,” said researcher John Clinton.

Ten o’clock
What is also very striking is that the Marsquake was present for no less than 10 hours. And it’s surprisingly long. In fact, no previously detected tremors have lasted longer than an hour. During those ten hours, the researchers also noticed surface waves traveling along the crust and upper mantle for the first time. “These waves circled the globe several times,” Clinton said.

Epicenter
Upon further analysis, it appears that the epicenter was near, but still just outside of Cerberus Fossae; the most seismically active region of the red planet. And it’s strange. The location of the epicenter cannot be associated with known geological features. This means that it is still unclear exactly how the worst measured Mars quake originated. The cause may include features hidden deeper in the planet’s crust, although this remains speculation.

Volcanically active
Incidentally, just like on Earth, most detected Martian earthquakes are believed to occur due to sudden changes in the crust. How this happens remains an open question. Here on Earth, earthquakes are usually caused by the tectonic plates that make up the Earth’s surface moving in relation to each other. However, the surface of Mars is not made up of plates. Therefore, the earthquakes are suspected to originate from volcanically active areas on the Red Planet.

High and low frequency waves
Finally, the May Marsquake was exceptional for one last reason. Scientists suspect that Martian earthquakes come in “two flavors”. On the one hand, we know high frequency waves characterized by rapid but short vibrations. On the other hand, we are familiar with low frequency waves, in which the surface moves slowly, but with greater amplitude. May’s Marsquake was rare, having both high-frequency and low-frequency characteristics. “Perhaps this means that the previously recorded low- and high-frequency tremors are actually two sides of the same coin,” Kawamura speculates.

While the researchers’ study answered some questions about Marsquake’s record, it also raised new questions. Whether Insight can still help answer this is doubtful. Martian dust falling on its solar panels is slowly but surely killing the lander. In recent months, researchers have seen how the lander is losing more and more power. Insight should therefore not have long to live. “However, we are very happy that towards the end of Insight’s working life, we were able to witness this remarkable event,” Kawamura said. “Based on the data collected, I can only say that the mission was an extraordinary success.”