Peek beneath the Martian surface with ambient noise

Since the landing of NASA’s InSight unmanned probe on Mars in November 2018, the probe has used a seismometer – the Mars Seismic Service – to assess earthquake activity on the planet to draw conclusions about the planet’s internal structure.

In July, the ETH Zurich team, in collaboration with the Swiss Seismological Service (SED), provided rough insights, for example, on the thickness of the Martian crust, Martian mantle and diameter of the molten core.

However, structures close to the surface cannot be identified in this way, except by drilling. Meanwhile, researchers at ETH Zurich have taken an extra step: they used ambient noise on Mars (“ambient noise”) to determine local geology. This technique is used on Earth, for example, to see if Earth’s interior is weakening or amplifying seismic waves. From this, the seismic hazard of a site can be determined and areas of unstable landslides in mountains or in lakes can be analyzed.

Although there are many sources of noise available on Earth, Wind is the only remaining source of ambient noise for researchers on Mars.

Your geological findings They have now published the history of Mars at depths ranging from a few tens to two hundred meters in Nature Communications.

Unlike Earth, there is no plate tectonic activity on Mars. It is formed by phases of active volcanic activity. A large area is covered with a plateau of basaltic lava. The analysis by ETH Zurich provides a detailed subsurface overview of the Insight landing site. The top layer consists of three meters of sand (regolith) and loose rock about 20 meters thick, which was fractured by the meteorite impact. Below is a layer of lava flows that, according to publications, covered the planet from 1.7 to 3.6 billion years ago.

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Lava layers are divided by deposits located at a depth of 30 to 75 meters. Seismic images of geological layers have allowed researchers for the first time to understand the most important geological events that have occurred at the InSight landing site on Mars over the past three billion years.


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