We present the results from a mid-term monitoring activity carried out at the submarine hydrothermal system located off Panarea Island (Aeolian Islands, Italy). The collected data concern multiparametric information from a self-operating seafloor station (acoustics and chemical–physical parameters) acquiring data at regular intervals and transmitting it twice a day in near real-time. The acoustic records were analysed with the principal aim of investigating bubbling variations related to gas flow rate. Several anomalies have been documented, in the bubbling activity detected at high frequencies (100–2000 Hz), as well as in very low acoustic frequencies, related to fluids dynamic along cracks. An astonishing correlation between soil CO ₂ flux emissions recorded at Stromboli craters and the acoustic signals in the 1–30 Hz range has been identified, suggesting how this tectonic link could act as an escape route for fluids characterized by a shared source.

Marine hydrothermal ecosystems represent extreme environments connected to submarine volcanic areas characterized by vents, having high temperatures and particular chemical compositions. The hydrothermal marine system of Panarea, located in one of the seven small islands belonging to the Aeolian Archipelago (southern Tyrrhenian Sea), is characterized by a range of vents exhibiting diverse physical and chemical conditions. We aimed to analyze the microbial community of a peculiar hot spring belonging to the Panarea hydrothermal field, known as “Black Point” (BP), in two separate sampling expeditions (May and August). Our results demonstrated that the chemical–physical variations within this hydrothermal vent, such as temperature fluctuations, mineral content, and hydrothermal fluid dynamics, play a role in shaping the structure and diversity of microbial communities. The differences between the two sampling expeditions suggest that seasonal changes, i.e., in temperature, pH, and redox potential (Eh), could drive microbial community shifts over time.

Volcanic eruptions stand as formidable threats to adjacent communities, unleashing a spectrum of hazards such as earthquakes, tsunamis, pyroclastic flows, and toxic gases. The imperative for proactive management of volcanic risks cannot be overstated, particularly in densely populated areas where the potential for widespread devastation looms large. Kolumbo, an active submerged volcano located approximately 7 kilometers northeast of Santorini Island in Greece at 500m depth, serves a pertinent case. Its historical record is marred by an eruption in 1650 AD which triggered a relentless tsunami. The aftermath witnessed havoc on neighboring islands, coupled with casualties stemming from noxious gases in Santorini. Eyewitness accounts mention maximum water run-up heights of 20m on the southern coast of Ios, a staggering 240m inundation on Sikinos, and a disconcerting flooding of up to 2km² of land on the eastern coast of Santorini.Recent studies suggest that a potential future explosive eruption of Kolumbo poses a substantial hazard to the northern and eastern coasts of Santorini. Unfortunately, the absence of a concrete management protocol, leaves these areas vulnerable to an impending threat that demands immediate attention. Therefore, it is recommended that a comprehensive approach be adopted, involving scientific research (active monitoring, hazard maps), community engagement, preparedness planning with government agencies, and the development of timely response strategies to reduce the associated risks, prevent casualties, and mitigate the consequences on the region's economy and infrastructure. Our team has multidisciplinary data from past oceanographic expeditions that will help us to understand Kolumbo’s behavior. These include a) High-resolution multibeam bathymetry data and optical data., b) a dense network of sub-seafloor seismic reflection profiles, c) a series of the seafloor and sub-seafloor samples of microbial mat and sediments, d) CTD data, e) several polymetallic (Au, Ag, As, Sb, Pb, Hg, Mo, Zn, Cu, Tl) CO2 diffuser chimney samples and f) tephra in marine sediment cores. Despite the current knowledge that we managed to obtain, monitoring is needed to efficiently assess potential hazards and create early warning systems and management protocols for an imminent eruption from Kolumbo. In the current context, advanced sensors have been deployed to monitor Kolumbo's active hydrothermal field as part of the SANTORY project. The SANTORY project aims to create innovative communication tools and establish interregional monitoring protocols, providing the scientific community, policymakers, and stakeholders with the means to assess hazard warning codes effectively.

Shallow Hydrothermal Vents (SHVs) are fluid emission spots in which water dynamics are characterised by interactions between seawater and free gas due to low hydrostatic pressure. This characteristic marine environment represents a peculiar natural laboratory where the study of geo-biological conditions needs a multidisciplinary approach to better understand the extreme ecosystem dynamics.Although many studies have been already performed on physical-chemical conditions, analysing major chemical species, just a few studies have adopted multidisciplinary approaches, giving a broader and more detailed view of the observed phenomenon.We propose a multidisciplinary study carried out in the period May-August 2022, based on the geophysical, geochemical and biological analysis of Black Point (23m b.s.l.), a hydrothermal spring belonging to the system located at about 2 miles off the coast of Panarea island (Aeolian Archipelago, Italy). Here a multiparametric seafloor observatory is installed (IPANEMA Project funds), equipped with chemical-physical sensors, a hydrophone and a seismometer. The area is periodically monitored by scientific divers performing discrete geochemical sampling, in addition, acoustic radiation studies are regularly conducted close to the emission, to characterise their acoustic signatures and peculiarities in turn. The gained expertise has led to the development of custom algorithms to perform spectral analysis of the acoustic features.Comparing the variation of the flux, investigated through the inversion of acoustic energy (radiated in the band [35 - 55] Hz likely associated with the mass flux variation), with fluctuations related to the environmental seafloor temperature, both series exhibit synchronous relative maxima over the investigated period.Coupling these trends with geochemical and biological variations in terms of Minor, Trace elements and Rare Earth Elements (REEs) concentrations and in the microbial community, simultaneous variations have been highlighted as well.In detail, the highest concentrations of minor elements (Al, Fe, Mn), trace elements (As, V) and REEs correspond to spectral energy and temperature peaks. Moreover, pH is inversely correlated to Fe, Al and Mn, indicating its role in dissolution/precipitation of Fe, Al and Mn oxy-hydroxides; inversely, REEs are positively correlated to Fe, Al and Mn indicating the role of the oxy-hydroxide ligands in fractionation of these elements, as a consequence, REEs patterns shapes show LREE depletion (Lan/Ybn < 1).Furthermore, the composition and diversity of microbial communities were investigated by extracting metagenomic DNA from different matrices (vent fluid, marine sediment near the vent and seawater at a short distance from the vent) and through the next-generation sequencing of a bacterial marker gene (16S rRNA gene). The results show significant differences in the microbial community between the samples and in the two samplings (May and August), especially in the fluid vent. These results are in accordance with the geochemical flux variations and the seafloor temperature, suggesting that each sample carries its specific bacterial fingerprint and the microbial community changes depending on the physicochemical conditions.This study confirms the importance of a multidisciplinary approach as the key to highlight different features of SHVs and how geo-biological fields are strictly linked in extreme environments.

SANTORY is a state-of-the-art project dedicated to advancing submarine volcanic hazard monitoring and risk mitigation in the Aegean Sea. Located in Kolumbo submarine volcano, northeast of Santorini Island, this groundbreaking observatory employs advanced imaging, geophysical and geochemical measurements, and real-time monitoring technologies to address one of the most significant volcanic threats in the region.Over the past two years, SANTORY has provided unparalleled insights into Kolumbo’s geological dynamics and processes and potential hazards. High-resolution 3D mapping has identified steep slopes, mass-wasting deposits, and hydrothermal vent fields, crucial for assessing seafloor instability and the risks associated with eruptions and submarine landslides. Novel hyperspectral imaging and autonomous video systems have documented persistent hydrothermal venting, bubbling plumes, and environmental changes, offering a comprehensive baseline for tracking volcanic activity and geohazard precursors.Autonomous sensors on the crater floor have continuously monitored hydrothermal outflow temperature, pressure, and fluid chemistry, capturing variations driven by tides and magmatic activity. These continuous datasets are critical for identifying precursor signals of volcanic unrest, such as changes in subsurface permeability and magmatic degassing. Chemical and isotopic analyses of hydrothermal fluids have confirmed the degassing of CO2-rich fluids with a mantle-like 3He/4He signature, underscoring Kolumbo’s potential for hazardous eruptions and its significance as a high-risk volcanic system.SANTORY goes beyond scientific exploration; it is a transformative initiative aimed at improving volcanic hazard assessment and developing mitigation protocols. By integrating cutting-edge technologies and multidisciplinary expertise, the project delivers actionable insights to enhance early warning systems and protect vulnerable coastal communities.