From Outer Space to Sub Surface: Seismic Vibrations and the impact of COVID-19 Lockdown

On July 15, 2020, Artash Nath gave a presentation on Seismic Vibrations, their role in astronomy, how to measure them, and on what impact the COVID-19 lockdown has had on these vibrations. The presentation was delivered by Artash at the online Recreational Astronomy Night meeting of the RASC, Toronto Centre, Canada.

In his presentation, Artash talked about the dual role of seismic vibrations. For some astronomical observations such as detection of gravitational waves by LIGO, they are considered as external noise that need to be eliminated. For other astronomical observations such as understanding the surface and interior geology of the planets, they are the desired and valuable signals. Custom equipments have been made and sent other celestial bodies to gather data on seismic vibrations.

Instruments were sent to the surface of moon during the Apollo Missions (1969-1972) to study lunar quakes. Instruments were also sent aboard the Viking Landers (1976) to Mars to capture the seismic vibrations. Did they work, what data they captured and what we learnt from them?

More recently, the NASA Mars Insight that landed in the Elysium Planitia region of Mars on 26 Nov 2018 carried SEIS (Seismic Experiment for Interior Structure) – a round, dome-shaped instrument to measure Marsquakes.

The presentation talked about how seismic vibrations observed on Moon and Mars are different from each other and those that occur on Earth, why do they occur and what they tell us about planet formation and their geological features.

Interestingly the quakes on Mars and Moon last longer than quakes on Earth as there is no damping of the vibrations due to water bodies and the broken crust. However the magnitude (energy released) by these quakes is far smaller than those of the Earth.

Artash later talked about seismic stations set up on Earth, the data they capture and how to access it. He also shared the results of the comprehensive study he did about how seismic vibrations on Earth quieted during the COVID19 lockdown. The study was done for 6 Canadian cities.