Unusual seawater flooding in Marsascala last Saturday morning was caused by a seiche, the head of the University's Physical Oceanography, Aldo Drago,has explained.
Sea water flowed in beyond the Marsascala shoreline, seeping into some shops, when a sudden change in atmospheric pressure forced low waves into the bay, Prof Drago said.
Residents were taken aback when the sea at first retreated from the shore, exposing the bottom of the bay, before water gushed back onto the land covering the pavement , Marsascala mayor Mario Calleja said, adding that no damage was reported.
Prof Drago explained that fishermen called this phenomenonas a milgħuba. The one on Saturday was the largest one ever registered since the unit started recording data in 1993. It reached the one-metre range and was particularly intense between 7 and 10.30 a.m.
Prof. Drago explained that a seiche was caused when a change in atmospheric pressure acted like "an enormous hammer" pressing against the sea and causing waves to form.
Due to the bay being enclosed, the water oscillated - like water in a bath tub sloshing from one side to the other - and as a result waves could be seen moving out and back into the bay.
This was similar to the wave action caused by a tsunami but, unlike a tsunami, a seiche was not the result of an earthquake, Prof. Drago explained.
Alex Cutajar, the owner of Summer Nights Guest House Pub and Grill, said the water seeped into his premises located across the bay.
"The water looked disturbed... as though the top layer and bottom part of the sea were going in different directions. The wave would make its way onto the shore forcefully, then seep out slowly only to return a few minutes later."
Mr Cutajar, 53, said he was brought up in the area and, while he remembered high tides, he never recalled that extent of flooding.
Prof. Drago added that the phenomenon was not restricted to a location and may have also been noticed along other parts of the coastline particularly in Marsaxlokk bay, Grand Harbour, Msida and Għadira.