This post was originally published on here
A new study published in Scientific Reports describes the discovery of an unusually large hydrothermal vent field on the shallow seafloor surrounding the Greek island of Milos. The vents were found during the METEOR expedition M192, when scientists carried out detailed surveys using multiple techniques. These included underwater mapping tools as well as autonomous and remotely operated vehicles, which allowed the team to closely examine the seafloor.
The surveys revealed previously unknown hydrothermal activity at depths ranging from 100 to 230 meters. As a result, Milos is now recognized as hosting one of the largest shallow to intermediate depth hydrothermal systems in the Mediterranean, significantly reshaping scientists’ understanding of vent activity in this region.
Fault Zones Shape Where Vents Appear
Researchers identified three main vent regions known as Aghia Kiriaki, Paleochori-Thiorychia, and Vani. All three are positioned along active fault zones that cut across the Milos shelf. These faults are part of a broader geological structure called the Milos Gulf-Fyriplaka graben, a tectonic depression that has caused sections of the seafloor to sink to depths of up to 230 meters. The close match between the locations of the vents and these fault systems highlights the strong influence of tectonic forces on where hydrothermal fluids are able to reach the seafloor.
A Surprising and Visually Striking Discovery
“We never expected to find such a large field of gas flares off Milos,” says Solveig I. Bühring, senior author of the study and scientist at the MARUM — Center for Marine Environmental Sciences, University of Bremen, who led the expedition M192 during which the vents were discovered. “When we first observed the vents through the ROV cameras, we were stunned by their diversity and beauty — from shimmering, boiling fluids to thick microbial mats covering the chimneys.”
Tectonic Controls Revealed in Vent Patterns
First author Paraskevi Nomikou of the National and Kapodistrian University of Athens explains that the arrangement of the vent clusters closely mirrors the island’s underlying fault structure.
“Our data clearly show that the gas flares follow the patterns of the major fault systems around Milos,” Nomikou explains. “Different fault zones influence different vent clusters, especially where several faults meet. These tectonic structures strongly control how and where hydrothermal fluids reach the seafloor.”
Why Milos Matters for Earth Science
Together, the findings show how ongoing fault movement and long term geological activity have guided the formation and evolution of these vent fields. With this discovery, Milos stands out as one of the most important natural sites in the Mediterranean for exploring how tectonics, volcanism, and hydrothermal processes interact beneath the sea.
The results are also significant for the MARUM-based Cluster of Excellence “The Ocean Floor — Earth’s Uncharted Interface.” Building on this work, researchers are planning a follow up expedition to Milos, the Kolumbo submarine volcano near Santorini, and Nisyros. The study reflects close cooperation between Greek and German research institutions, including the National and Kapodistrian University of Athens, MARUM — University of Bremen, Friedrich-Alexander-Universität Erlangen-Nürnberg, ICBM — Institute for Chemistry and Biology of the Marine Environment Oldenburg, and Constructor University Bremen.
Participating institutions:
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens (Greece)
- School of Science, Physics & Earth Sciences, Constructor University Bremen, Germany
- Faculty of Geosciences, University of Bremen
- MARUM — Center for Marine Environmental Sciences, University of Bremen
- GeoZentrum Nordbayern, Friedrich-Alexander-University Erlangen-Nuernberg
- ICBM — Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University of Oldenburg
