The English vocabulary contains a few words that only make sense from an earthly point of view. Earthquake is one of them. Even in some science fiction and fantasy books where the action takes place in a location other than earth, this team is used to denote the shaking of the ground. It is therefore nice to see planetary scientists trying to extend the root word to other planets. Marsquakes are the most widely studied. Thanks to InSight, scientists have now collected data on Marsquakes for a full year for the first time.
Headed by Savan Ceylan from ETH Zurich, the team presented its results at the 2021 annual meeting of the Seismological Society of America. The data was collected using the SEIS seismometer, an InSight instrument that physically touches the surface of Mars. It was extremely tedious as Marsquakes are generally much weaker than their earthen cousins, with the maximum amplitude on the Richter scale being 3.6.
Simulation of how one more marsquake would go through the planet.
Credit: NASA / JPL-Caltech / ETH Zurch / Van Driel
Patterns could also be seen in the data. Marsquakes apparently come in two flavors – high frequency and low frequency. High frequency waves move in the crust around the planet and seem to last much longer, like moonquakes do. Low frequency waves use the mantle as the main means of transportation and die out much more quickly, similar to earthquakes.
Another pattern that scientists have been looking for is called “seismic phase arrivals”. This happens when different types of seismic waves of an event arrive at a location in a different order. This sequence allows scientists to perform a technique similar to triangulating a radio signal and locate the source of the Martian quakes. Interestingly, all of the marsquakes associated with a seismic phase arrival pattern came from the same part of the planet – Cerberus Fossae, which is approximately 1,800 miles from InSight’s location.
False color image of the Cerberus Fossae region.
Photo credit: NASA / JPL / University of Arizona.
Cerberus Fossae is a relatively young red planet feature that is still being studied to determine what makes it geologically active. Tools like SEIS are one way of determining this. Scientists who want to use this data, however, have to grapple with one of the biggest problems facing the sensor world – noise.
In some ways, the seismological noise on Mars is easier to deal with than that on Earth. There are no waves hitting the crust all the time, and the thin atmosphere is calm at night. Even the slight atmospheric disturbance on Mars can interfere with the readings, as can other unwanted noise from the weather and from the lander itself.
Illustration of how Insight can detect tremors in different locations.
Photo credit: Giardini et al
Dr. Ceylan’s team succeeded in devising a filtering method that would allow them to properly understand even the very small Marsquakes that InSight was able to capture. With this filter comes a better mechanism for future studies of the seismological activity of Mars. One day there might even be people on the planet who will place seismometers in even more interesting places. Then we will really be able to understand the difference between an earthquake and a Mars quake.
Learn more:
SSA – Seismicity on Mars full of surprises in the first year of continuous data collection
UT – After a challenging first year on Mars, InSight shows us that Mars is seismically active
UT – InSight has already detected 21 earthquakes
UT – InSight has just discovered its first “Marsquake”
Learn picture: Picture of Mars.
Photo credit: NASA / JPL – Caltech / ETH Zurch / Van Driel
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