Chapter 1: Introduction to Martian Seismology

The occurrence of a marsquake on April 6 marked a groundbreaking moment in the exploration of Mars. This tremor represents the first seismic activity ever recorded on the Red Planet, concluding a 40-year quest for such phenomena and paving the way for a fresh field of study: Martian seismology.

The SEIS (Seismic Experiment for Interior Structure) instrument, which traveled to Mars aboard the InSight lander, was responsible for detecting this tremor. This dome-shaped device can sense seismic activities deep within Mars' surface, as well as disturbances caused by environmental changes or asteroid collisions.

Philippe Lognonne, the lead of the SEIS team from the Institut de Physique du Globe de Paris (IPGP) in France, expressed his excitement: “We’ve been waiting months for a signal like this. It’s so thrilling to finally have evidence that Mars is still seismically active. We look forward to sharing detailed results after we analyze the data.”

The SEIS instrument on the Martian surface. Image credit: NASA/JPL-Caltech

The exact cause of this marsquake remains uncertain. It may stem from stress due to the thermal expansion and contraction of the Martian surface. Variations in the materials can affect the speed of seismic waves, granting geologists insights into the planet's underlying structure. Unfortunately, this particular event was too minor to provide significant details about the Martian crust. The SEIS probe is operated by France's National Centre for Space Studies (CNES).

Chapter 2: A Historical Perspective on Martian Quakes

This video discusses how Mars settlers will adapt to survive marsquakes, highlighting challenges and innovations.

The quest to detect seismic activity on Mars began over 40 years ago with NASA’s Viking landers, which aimed to uncover quakes on the planet. However, these missions failed to register any seismic events.

“Among all the recorded activities, only one possible earthquake candidate was identified during the Viking mission,” SEIS engineers reported. Unfortunately, due to the lack of meteorological data, it was impossible to confirm whether this vibration was genuinely related to seismic activity or merely the result of wind disturbances.

After several canceled missions over the decades, InSight successfully landed a seismometer on Mars on November 26, 2018, marking the first deployment of such an instrument since the Viking era.

The SEIS seismometer being set up on Mars, December 19, 2018. Image credit: NASA/JPL-Caltech

While seismometers on the Moon, installed by Apollo astronauts, have experienced both triumphs and setbacks, they have significantly contributed to our understanding of lunar geology. The first true moonquakes were often misidentified, but the data gathered between 1969 and 1977 from over 10,000 recorded events helped scientists understand the Moon's geological structure and its formation.

Chapter 3: Understanding Seismic Activity on Mars

This video showcases NASA's detection of the first likely marsquake, shedding light on the planet's seismic history.

Unlike Earth, where the crust is rife with seismic noise, Mars’ surface allows for the detection of subtle tremors. On Earth, similar quakes would be overshadowed by the cacophony of ocean waves and frequent tremors, particularly in tectonically active regions. Mars and the Moon lack the tectonic plate movements that cause earthquakes on Earth; instead, their quakes are likely caused by thermal stresses in the crust.

Tom Pike from Imperial College London stated, “We worked tirelessly to create the most sensitive silicon sensors on Earth to send to Mars as part of SEIS. We were uncertain if they would perform adequately, but it appears that Mars, while much quieter than Earth, is providing us with seismic signals we can detect. Our initial investigation into the interior of another planet has now commenced.”

By analyzing quakes on Mars, researchers aim to gain insights into the geological history of both the Red Planet and Earth, enhancing our understanding of how these celestial bodies formed billions of years ago.