Large underwater tsunamis registered

(ORDO NEWS) — Scientists from the British Antarctic Survey and the University of Exeter have registered large underwater tsunamis that are formed when icebergs break away from glaciers.

This process causes global mixing of the surface layer of the oceans.

On January 21, 2020, a kilometer-long front of the William Glacier (Anvers Island) broke off in Bergen Bay off the coast of the Antarctic Peninsula.

Although the amount of ice lost is not known, scientists have estimated that 3-20 million cubic meters of ice was dumped into the sea, and the potential energy released into the ocean was 0.6-2.4 trillion Joules.

Similar events on the Williams Glacier occur 1-2 times a year, the reason for which is the ongoing retreat of ice shelves due to global warming.

The calving of the glacier was directly observed by the British research vessel RRS James Clark Ross which carried out oceanographic measurements in Bergen Bay.

It turned out that the breakaway of the glacier led to a large-scale mixing of the water of the entire bay, making the layers of sea water much more uniform in temperature.

The collected data indicate that the thermal mixing was caused by the rapid propagation of large amplitude underwater waves, called underwater tsunamis, due to calving.

The ice break doubled the kinetic energy of internal waves – density fluctuations in the sea water column – which remained elevated for at least two days after the event.

The propagation of internal tsunamis beyond the mouth of Bergen Bay most likely took place, however, due to the bottom topography, most of the energy remained in the fjord.

However, surface tsunamis and internal waves, if left unchecked, can travel very long distances in the ocean, affecting both the nutrient supply of the sunlit ocean layer and its stability.

With global warming, the frequency of this phenomenon may increase.


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