🌋 A major hydrothermal system discovered in the Mediterranean

How can boiling water springs emerge so close to the shores of a Mediterranean island? This geological question has been answered by a team of researchers who uncovered a hydrothermal field of unexpected scale around Milos, Greece. This discovery overturns existing models about the distribution of these underwater phenomena.

During the METEOR M192 expedition, scientists explored the submarine plateau of the island of Milos using state-of-the-art tools, including autonomous and remote-operated vehicles. This equipment allowed them to precisely map the seafloor and reveal active hydrothermal vents at depths ranging from 330 to 750 feet (approximately 100 to 230 meters) (see below). This observation immediately surprised the scientific community due to its scale and location.


Three main vent areas were identified: Aghia Kiriaki, Paleochori-Thiorychia, and Vani. All these sites are located along active faults that traverse the Milos plateau. These geological fractures are part of a major tectonic depression, the Milos-Fyriplaka Gulf graben, which has lowered the seafloor to depths of up to 750 feet (approximately 230 meters). The correlation between the vent locations and these structures indicates a direct influence of tectonic forces.

The collected data shows that hydrothermal gases and fluids follow the paths of the fault systems around Milos. Solveig I. Bühring, the expedition leader, expressed astonishment at the diversity of the vents, ranging from bubbling fluids to colorful microbial mats. Paraskevi Nomikou clarified that different fault zones distinctly affect vent clusters, particularly at the intersections of several fractures.

This discovery places Milos among the most extensive shallow hydrothermal systems known in the Mediterranean. It significantly broadens the understanding of the distribution of these vents in the region and illustrates how ongoing geological processes shape their evolution. Consequently, the island becomes a privileged study site to explore the interactions between tectonics, volcanism, and hydrothermal activity.

Research prospects are promising, as these vents offer unique conditions for studying extreme microbial life and geochemical cycles. Future missions could delve deeper into the impact of these structures on local marine ecosystems and their role in the geological dynamics of the Aegean Sea, paving the way for new scientific advances.

Hydrothermal vents: underwater oases

Hydrothermal vents are fissures in the ocean floor through which hot, mineral-rich fluids escape. They typically form near mid-ocean ridges or volcanically active areas, where seawater seeps into the Earth's crust, is heated by contact with magma, and rises laden with chemical substances.

These environments harbor unique ecosystems, based on chemosynthesis rather than photosynthesis. Organisms such as tubeworms or specialized bacteria thrive in these extreme conditions, using sulfur compounds or methane as an energy source. This makes them models for studying life in hostile environments, even for understanding the origins of life on Earth.

The discovery of shallow vents, like those at Milos, allows observation of these processes at accessible depths. This facilitates research into how fluids interact with rocks and seawater, influencing ocean chemistry and mineral deposits. These sites are also valuable indicators of submarine geological activity.

The study of hydrothermal vents contributes to various fields, from marine biology to geology, including research on mineral resources. They reveal how the Earth redistributes heat and materials, playing a role in the global cycle of elements and offering lessons on the resilience of life.

The role of tectonic faults in marine geology

Tectonic faults are fractures in the Earth's crust where rocks move relative to each other. In marine environments, these structures are often associated with areas of plate divergence or convergence, creating submarine features like grabens or ridges. They act as conduits for fluids, allowing the circulation of water, gases, and minerals.

In the case of the island of Milos, the active faults of the Milos-Fyriplaka Gulf graben have lowered the seafloor, facilitating the emergence of hydrothermal fluids. These fractures control the location of vents by providing preferential pathways for the upward flow of deep-heated waters. Where several faults intersect, they can create concentration points where activity is more intense.

This tectonic control is observable in many regions of the world, such as the Mid-Atlantic Ridge or the Pacific Ring of Fire. It explains why some vents are clustered in extensive fields, while others are isolated. Understanding these mechanisms helps predict where to find new hydrothermal sources and assess geological risks.

Faults also influence the formation of mineral resources and the stability of the seabed. Their study allows for a better understanding of sedimentation processes, the evolution of ocean basins, and the interactions between tectonics and volcanism.