Flooding in Msida on Thursday was caused by a phenomenon known as an “atmospheric tsunami”, according to scientists.
The roundabout surrounding the Workers’ Memorial monument was flooded with seawater yesterday, leading some social media users to question where the water had come from.
Photos and videos posted online showed vehicles passing through the flooding at the busy intersection, with water rising several inches above the road by midday. One social media user called the sight “weird, like the sea went up to the streets”.
But, according to scientists from the University of Malta, the water was the result of a phenomenon known as a “meteotsunami”, or “atmospheric tsunami”.
The phenomenon occurs when changes in atmospheric pressure cause the sea level to rise or fall, with higher atmospheric pressure leading to lower sea levels, and vice versa.
“Think of atmospheric pressure like a hand pressing down on the sea,” explained Dr Anthony Galea, a senior lecturer at the University of Malta’s geosciences department.
“If the atmospheric pressure is greater, it pushes the water down more; when there is less pressure, the sea level rises,” he said.
Pointing to readings collected by instruments measuring atmospheric pressure in Msida and Mgarr, in Gozo, Galea noted the country had been experiencing fluctuating pressure levels since Wednesday night. And this, he said, had led to rising and falling sea levels.
Asked if the flooding was the result of a coastal seiche, or milgħuba - a similar phenomenon which has occurred in Msida and other areas of the country before – the lecturer said he did not think so.
He explained that while seiches tend to be in response to large pressure changes elsewhere – for example, a storm elsewhere in the Mediterranean – and feature sea levels that either rise or fall before returning to their original state, meteotsunamis are more variable, fluctuating over time in response to constantly changing pressure levels.
But Galea stressed that while the phenomenon might have the word “tsunami” in the title, it shouldn’t be confused with the towering walls of water favoured by Hollywood blockbusters.
Commenting on the situation in Msida “and other localities”, the University of Malta Oceanography Malta Research Group – of which Galea is a member – said in a Facebook post it had detected the meteotsunami using “cutting-edge sea level radars and atmospheric sensors” along the coast.
“You might not have felt it but you could definitely see it,” the group said of the phenomenon.
And while the phenomenon might have provoked curiosity, residents could be grateful the flooding had not been more severe; last summer, at least two vehicles were dragged into the sea after seiche waves caused the sea level to rise in many coastal areas.