A recent study offers strong evidence that a massive ‘megaflood’ helped replenish the Mediterranean Sea, concluding an era when the region was predominantly covered by salt flats. This research indicates that the Zanclean Megaflood marked the end of the Messinian Salinity Crisis, which occurred between 5.97 and 5.33 million years ago.
A recent study offers strong evidence that a massive ‘megaflood’ helped replenish the Mediterranean Sea, concluding an era when the region was predominantly covered by salt flats.
According to the study, the Zanclean Megaflood put an end to the Messinian Salinity Crisis, an event that unfolded from 5.97 to 5.33 million years ago.
An international team of researchers, which includes experts from the University of Southampton, has identified geological features in Southeast Sicily that indicate a significant flood event in the area.
“The Zanclean megaflood was an astonishing natural occurrence, with water discharge rates and flow speeds far exceeding any other known flooding events in Earth’s past,” stated Dr. Aaron Micallef, the study’s lead author and a researcher at the Monterey Bay Aquarium Research Institute in California. “Our findings present the most convincing evidence yet for this remarkable event.”
During the Messinian Salinity Crisis, the Mediterranean became cut off from the Atlantic Ocean, leading to evaporation and the formation of extensive salt deposits that dramatically altered the region’s topography.
For a long time, scientists believed that this arid period concluded gradually, with the Mediterranean refilling over roughly 10,000 years. However, this assumption was challenged by the discovery of an erosion channel stretching from the Gulf of Cadiz to the Alboran Sea in 2009, suggesting a singular, massive flooding event that lasted between two and 16 years, referred to as the Zanclean megaflood.
It is estimated that the megaflood had a discharge rate ranging from 68 to 100 Sverdrups (Sv), where one Sv equates to one million cubic meters per second.
The new findings, published in the journal Communications Earth & Environment, integrate newly identified geological features with geophysical data and numerical modeling to provide the most detailed understanding to date of the megaflood.
The researchers examined over 300 asymmetric, streamlined ridges within a corridor across the Sicily Sill, a submerged land bridge that once divided the western and eastern Mediterranean basins.
“The shape of these ridges suggests they were formed by large-scale, turbulent water flow primarily moving in a north-easterly direction,” explained Professor Paul Carling, an Emeritus Professor in the School of Geography and Environmental Science at the University of Southampton and a co-author of the study.
“They illustrate the tremendous force of the Zanclean Megaflood and its impact on the landscape, leaving permanent marks in the geological record.”
By analyzing the ridges, the team discovered they were capped with a layer of rocky debris consisting of material carried away from the ridge sides and nearby areas, indicating it was deposited rapidly and with great force.
This layer sits at the transition between the Messinian and Zanclean periods, corresponding to the time when the megaflood is believed to have transpired.
Applying seismic reflection data—a type of geological ultrasound that reveals rock and sediment layers below the surface—the researchers found a ‘W-shaped channel’ on the continental shelf east of the Sicily Sill.
This seabed channel connects the ridges to the Noto Canyon, a deep underwater gorge in the eastern Mediterranean.
The channel’s shape and placement suggest it functioned like a large funnel. As the megaflood waters surged over the Sicily Sill, this channel likely directed the flow towards the Noto Canyon and into the eastern Mediterranean.
The team also created computer models to simulate the behavior of the megaflood. These models indicate that the flood’s direction changed and its intensity increased over time, achieving speeds of up to 32 meters per second (72 miles per hour), which allowed it to carve deeper channels, erode more materials, and transport them over greater distances.
“These discoveries not only illuminate a pivotal event in Earth’s geological history but also highlight how landforms have persisted for over five million years,” Dr. Micallef noted. “This paves the way for further investigation along the Mediterranean coasts.”
The research received backing from the National Geographic Society, Deutsche Forschungsgemeinschaft, and the David and Lucile Packard Foundation.
