NASA 'Shake Room' Reveals What Moonquakes and Marsquakes Feel Like

What do quakes on the moon and Mars fee like? A team of scientists in Switzerland has been shedding light on this question using a specially built quake simulator known as a "shake room."

Earth is not the only place that experiences quakes. We know from seismometers placed on the lunar surface 50 years ago by Apollo 11 astronauts that this phenomenon also occurs on the moon.

And on April 6, 2019, a piece of equipment known as the Seismic Experiment for Interior Structure (SEIS)—which was deployed on the Red Planet by NASA's InSight lander in 2018—measured the first confirmed "marsquake." SEIS has also recorded three other seismic events. However, the signals measured were much weaker and scientists aren't sure if quakes were responsible.

A team of scientists from ETH Zurich in Switzerland heads the InSight mission's Marsquake Service. As part of a video demonstration, they decided to experience for themselves the differences between quakes on Earth, Mars and the moon.

To do this the researchers fed seismic wave data from quakes on the moon, two of the events measured by SEIS and earthquakes into the simulator before stepping inside to feel the effects of each one.

"The simulator is able to replay ground motions that we record on seismometers," John Clinton, leader of the Marsquake Service at ETH Zurich, told Newsweek. "The simulator table moves in the same way the ground would have moved at the seismometer location during the quake. Crucially, we are able to amplify the motions as we like."

It should be noted though that the simulator does not provide an accurate demonstration of how marsquakes and moonquakes would feel for astronauts on these worlds because they are much weaker than those on Earth. As a result, the scientists had to amplify the seismic signals from these quakes by a factor of around 10 million before feeding them into the simulator.

"The extra-terrestrial events are extremely small, well below the threshold that people on Earth, or astronauts standing on the moon or Mars, would be able to feel," Clinton said. "What we are trying to demonstrate by showing the different planetary quakes in the shake room is that even if we amplify the motions from the different planetary bodies so they are roughly at a similar amplitude that people could feel, the types of shaking are very different."

On Earth, seismic waves created by quakes usually last anywhere between 10 seconds and a few minutes, but on the moon, they can persist up to an hour or more. This is due to the differences in geological structure between the crusts of the two objects.

For billions of years, the moon and the Earth have been struck by countless meteorites that fracture the crusts of these worlds. But unlike on Earth there is no volcanism on the moon. On our planet this has the effect of joining rocks in the crust back together via heating. There is also no erosion and deposition of materials due to the effects of wind and water on the moon, which also contribute to this joining process on Earth.

The Earth's crust is, perhaps surprisingly, far more homogenous than the moon's, leading to differences in how seismic waves propagate.

"On Earth, we record many earthquakes that span huge ranges in size," Clinton said. "The motions are very 'sharp', with abrupt, distinct shaking that is rich in different frequency content that we can easily associate with different types of waves passing through the Earth."

"On the Moon, during the handful of years the Apollo seismometers were operational, events were recorded that had very small amplitudes and were characterized by very long duration high-frequency signals, up to an hour, with energy that slowly increases then decreases," he said. "This is associated with the very fractured lunar surface."

Seismic data from Mars is much more limited, but marsquakes appear to have a duration somewhere in between earthquakes and moonquakes—around 10 to 20 minutes.

"On Mars, during the few months that InSight has been operational to date, we are also only seeing very small amplitude events," Clinton said. "They are neither like on Earth nor the moon. They are long—tens of minutes long—but not as long as on the moon, with between 5-20 minutes of energy. The larger events show sharp arrivals that suggest distinct packages like on Earth, followed by very diffuse energy like the Moon. For the majority of marsquakes, the energy is much longer period than on the moon."

Research into seismic activity on Mars and the moon can help shed light on the geology of these two worlds, and also the formation of planets in the early solar system.

This article was updated to include additional comments from John Clinton.

Seismic Experiment for Interior Structure
This image shows NASA's Seismic Experiment for Interior Structure, or SEIS, on Mars. NASA/JPL-Caltech