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Ground Deformation Caused by Atmospheric Gravity Waves on Mars: An Independent Assessment of Martian Crustal Rigidity

Seismic observations on extraterrestrial bodies always face challenges because we are forced to perform single-station seismology or sparse network seismology. The former is exactly the case of the NASA InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission, which conducted seismic and meteorological observation on Mars (2018 – 2022). In such a case, simultaneous observation of seismic and meteorological data (such as atmospheric pressure) is useful for estimating the internal structure of a planet. On Earth, the measurement of the ground deformation due to background pressure variations allows us to assess ground rigidity, known as Sorrells’ theory. Nowadays, this theory is applied to event-driven signals (e.g., convective vortices, gravity waves) not only on Earth but also on Mars.

Previous studies on Mars estimated the rigidity structure down to tens of meters, focusing on convective vortices, which excite energy around 0.5 – 1.0 Hz. To retrieve structure information from greater depth, this study pays attention to atmospheric gravity waves, whose energy range is around 1 mHz. In the analysis, we retrieved InSight’s seismic and pressure data for windows containing atmospheric gravity waves, computed the transfer function (the spectral ratio between pressure and horizontal acceleration), and then estimated Young’s modulus of the Martian crust. In the presentation, followed by an example of analysis for terrestrial gravity waves (especially the Lamb wave from the Hunga-Tonga eruption in 2022), we will present the results for Martian gravity waves and discuss the consistency with the structure obtained from analyses of Martian quakes.

Session: Special Applications in Seismology [Poster Session]

Type: Poster

Room: Exhibit Hall

Date: 5/1/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Keisuke Onodera

Student Presenter: No

Additional Authors