Team investigates significance of newly discovered hydrothermal fields off the island of Milos

The study identifies three major vent areas — Aghia Kiriaki, Paleochori–Thiorychia, and Vani — all located along active fault zones that run across the Milos shelf. These faults belong to a large tectonic depression, the Milos Gulf–Fyriplaka graben, which has lowered the seafloor to depths of up to 230 meters. The close alignment of vents with these geological structures shows that tectonic activity plays a key role in determining where hydrothermal venting occurs.

“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.”

According to first author Paraskevi Nomikou of the National and Kapodistrian University of Athens, the spatial pattern of these vent clusters is closely controlled by the island’s tectonic fabric:

“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.”

The findings demonstrate how active faulting and ongoing geological processes have shaped the evolution of these vent fields. This discovery establishes Milos as one of the most significant natural laboratories in the Mediterranean for studying the interplay between tectonics, volcanism, and hydrothermal activity.

The results are also relevant for the MARUM-based Cluster of Excellence “The Ocean Floor – Earth's Uncharted Interface.” A follow-up expedition to Milos, the Kolumbo submarine volcano off Santorini, and Nisyros is planned. The research is the result of close collaboration between Greek and German 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.

Original publication:

Paraskevi Nomikou, Konstantina Bejelou, Andrea Koschinsky, Christian dos Santos Ferreira, Dimitrios Papanikolaou, Danai Lampridou, Stephanos P. Kilias, Eirini Anagnostou, Marcus Elvert, Clemens Röttgen, Joely M. Maak, Alissa Bach, Wolfgang Bach, Areti Belka, Evgenia Bazhenova, Karsten Haase, Charlotte Kleint, Effrosyni Varotsou, Palash Kumawat, Erika Kurahashi, Jianlin Liao, Eva-Maria Meckel, Ignacio Pedre, Wiebke Lehmann, Enno Schefuß, Michael Seidel, Sotiria Kothri & Solveig I. Bühring: Structural control and depth clustering of extensive hydrothermal venting on the shelf of Milos Island. Scientific Reports volume 15 (2025). DOI: https://doi.org/10.1038/s41598-025-26398-y

Contact:

Dr. Solveig I. Bühring
Petrology of the Ocean Crust
MARUM – Center for Maine Environmental Sciences, University of Bremen
Email: sbuehring@marum.de

 

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

 

MARUM produces fundamental scientific knowledge about the role of the ocean and the seafloor in the total Earth system. The dynamics of the oceans and the seabed significantly impact the entire Earth system through the interaction of geological, physical, biological and chemical processes. These influence both the climate and the global carbon cycle, resulting in the creation of unique biological systems. MARUM is committed to fundamental and unbiased research in the interests of society, the marine environment, and in accordance with the sustainability goals of the United Nations. It publishes its quality-assured scientific data to make it publicly available. MARUM informs the public about new discoveries in the marine environment and provides practical knowledge through its dialogue with society. MARUM cooperation with companies and industrial partners is carried out in accordance with its goal of protecting the marine environment.

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