Participation to the Indian Ocean Geoid Low Expedition

A journey of seismological inquisitiveness into the depths of the Indian Ocean with ORV Sagar-Kanya.

 

               The Indian Ocean in the Southern Hemisphere: "Painting the sky"

 

The start – Expedition SK-348

The journey starts with a broad vision of the Indian Ocean Geoid Low (IOGL)- Programme, initiated by NCPOR, MoES, to understand the origin of the lowest geoid existing on the Earth. The lowest geoid appears to be a dent on Earth’s surface created due to low-density material lying beneath the Indian Ocean. Various theories have been put forth to explain its existence, of which a brief outlook can be viewed in Ningthoujam et al., (2019).

In May 2018, an array of 17 Ocean Bottom Seismometers (OBSs) was deployed in the Indian Ocean for 2 years to resolve and provide a scientific explanation to the IOGL. Unfortunately, I missed the initial journey.

 

Phase I- Recovery and Re-deployment – SK-360

A great success with 100% of OBS recovery in 2019. The data has been well received with a little interruption from strong persistent ocean noises such as Microseism and Compliance noise. These two strong dozers sometimes will not let you see the beautiful earthquake signals hidden beneath them. Thanks to researchers who are already working and playing with ocean seismological data for four long decades.

And just like “a pinch of salt to the ocean”, I initiated to contribute to this huge and complex domain of Ocean Seismology.

 The final resurrection - Expedition SK-368

 This time is different as we already know what the signals would be like. Unfortunately, it’s the COVID-19 era when nearly 99% of the world has been under lockdown and surprisingly noise levels are seen to be lowered during a few months of strict lockdown. The lowering of high-frequency noise from seismological stations on land has also been reported by various researchers (e.g., Lecocq et al., 2020). Somehow, it gives a way to understand how anthropogenic activity on land as well as at sea can contribute to resonating noise levels in the ocean.