Coastal waters in L-Aħrax tal-Mellieħa turned stunning shades of white and pale blue on Thursday, with a large plume of affected water extending out from the coast for a couple of kilometres.
A combination of different natural phenomena may be what to thank for the attractive vista, according to president of the Malta Chamber of Geologists Peter Gatt.
It is probably a whiting phenomenon- Geologist Peter Gatt
Rock erosion, disturbance of lime mud on the seabed and changes to the chemical composition of the water could be among the factors involved.
“It could be coastal erosion,” said Gatt, “but since this extends along a long stretch of coast it is probably a whiting phenomenon... [caused by] suspension of fine carbonate mud and precipitation of calcium carbonate in the sea.
“It could also have been a combination of all three,” he added.
When the sea is violently disturbed by strong winds, carbon dioxide is pushed out of the water, causing the sea to become less acidic. This causes tiny calcium crystals to form in the water, brightening its colour.
The seabed around Malta also contains large amounts of lime mud. When the sea is rough, this mud is churned up and released from the seabed, further whitening the water visible at the surface.
Photographer Mark Zammit Cordina captured the scene on Thursday from a nearby vessel.
Rock face probably collapsed recently
One of the crew pointed out to Zammit Cordina that the appearance of the rock face – showing lighter and darker sections – indicated it had probably collapsed recently, he said.
The affected area was also filmed on Thursday by St Julian’s resident Ray Azzopardi, who told Times of Malta he’d “never seen anything like it before”.
“I was there last week and didn’t see anything in the water then,” he said, adding that cracks in the cliff face and lighter shaded sections of rock visible on Thursday led him to speculate that erosion may have caused the change in colour.
The Environment and Resources Authority (ERA) confirmed it was investigating the incident but said it had not received prior reports of the occurrence before being contacted by Times of Malta yesterday afternoon.
Mellieħa mayor Mario Vella said the local council would be checking the area.
In February, gale-force winds caused by Storm Helios caused a boulder near Popeye Village to dislodge and fall onto one of the small structures of the popular tourist attraction below.
Coastal areas of Malta had been particularly battered by the severe weather, which included torrential rain pouring down for more than 24 hours.