Kolumbo Submarine Volcano serves as a Natural Laboratory in the active Hellenic Volcanic Arc
Tuesday, 31 January 2017: 08:30
Sovereign Room (Hobart Function and Conference Centre)
Paraskevi Nomikou1, Steven Carey2, Katherine Lynn Croff Bell3, Paraskevi Polymenakou4, Stephanos Kilias1 and Robert D. Ballard5, (1)National and Kapodistrian University of Athens, Athens, Greece, (2)Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States, (3)Ocean Exploration Trust, New London, CT, 06371, United States, (4)Hellenic Center for Marine Research, Anavyssos, Greece, (5)Ocean Exploration Trust, Narragansett, RI, United States
Abstract:
Kolumbo submarine volcano
is located just 7 km from the well-known Santorini volcanic islands. It is the most active and dangerous submarine volcano in the Mediterranean Sea, and its proximity to Santorini makes a better understanding of its hazards to the local population of critical importance. In 1650 AD, Kolumbo erupted explosively resulting in approximately 70 fatalities from toxic gases on nearby Santorini and significant coastal damage from tsunamis. Recent strong seismic activity in the Kolumbo volcanic field and the 2011-2012 unrest at Santorini has been attributed to magma movement underneath the Santorini volcanic field. The shallow crater of Kolumbo (<500 m depth) currently hosts a hydrothermal field with active and inactive sulfide-sulfate hydrothermal chimneys and mounds that are enriched in Au, As, Sb, Hg, Ag, Tl, and Zn, Pb (Fig.1). The hydrothermal system emits mantle-derived fluids consisting of nearly pure gaseous CO
2 together with aqueous fluids venting at 220
oC. Due to its isolated bowl-shaped geometry a dense stagnant layer of CO
2-rich water has accumulated inside the crater. This layer has caused bottom (~10-15 m) water acidification and dissolution of carbonate in the sediments. Unlike hydrothermal vents at MOR’s or other subduction-related arc volcanoes, the Kolumbo vents are devoid of vent-specific macrofauna. The only biological community that appears to thrive within the vent field consists of bacterial and archaeal colonies which suggests significant toxicity of the acidic fluids and associated trace element concentrations.
Kolumbo serves as a unique natural laboratory for interdisciplinary studies due to: (i) its accessible location, (ii) the variety of potential natural hazards, (iii) extreme environmental gradients, (iv) localized ocean acidification, (v) unique hydrothermal mineralization and associated ecosystems and (vi) the urgent need to assess hazards to nearby populations.
Fig.1: a) Detailed swath bathymetric map of the Kolumbo volcano generated from a ship multibeam echosounder, b, c, d) ROV photos of active high-temperature (220°C) hydrothermal vents discharging vigorously both gases (>99 % CO2) and fluids and e) Small pockmark–like crater discharging low-temperature (70oC) fluids through the Fe-bacterial mats that cover the entire crater floor of Kolumbo.
