South Aegean Volcanic Arc

South Aegean Volcanic Arc
Name	South Aegean Volcanic Arc
Photo caption	Map of the South Aegean region
Location	Aegean Sea, Greece
Type	Volcanic arc
Last eruption	1950s (Santorini/Kameni)

South Aegean Volcanic Arc The South Aegean Volcanic Arc is a chain of volcanic islands and submarine centers in the Aegean Sea associated with the subduction of the African Plate beneath the Eurasian Plate and the Hellenic Arc. The arc includes notable islands such as Santorini (Thira), Milos, Nisyros, Kos and Methana and lies near tectonic features named for regions like the Hellenic Trench and the Cretan Arc. It is important to regional geology, hazard assessment, and historical events in the eastern Mediterranean, interacting with sites such as Crete, Rhodes, Athens, Istanbul, and Cyprus.

Geology and Tectonic Setting

The arc forms where the African Plate converges with the Eurasian Plate along the plate boundary marked by the Hellenic Arc and the Hellenic Trench, influenced by rollback and slab dynamics similar to systems studied at the Andes and the Aleutian Islands. Regional deformation links to the Anatolian Plate escape toward the Marmara Sea and the East Anatolian Fault system, and to rift segments near the Gulf of Corinth and the Aegean Sea Plate. Bathymetric features such as the Cretan Basin and the Mykonos Basin reflect extensional back-arc processes analogous to the Mariana Trough and the Tyrrhenian Sea. The arc overlies crust that has been modified by Paleogene and Neogene collisions including fragments related to the Sazlıdere Complex and the Pelagonian Zone.

Volcanoes and Volcanic Centers

Major volcanic centers include stratovolcanoes and caldera complexes like Santorini (Thira) (Minoan eruption fame), monogenetic fields such as Methana, and large rhyolitic to andesitic systems like Nisyros and Milos. Submarine volcanoes and seamounts occur near Kolumbo and the Christiana-Santorini-Kolumbo volcanic field, while rhyodacitic centers are found on Kos and Tilos. Other named sites intersecting historical navigation routes include Saronic Islands volcanoes and the volcanic provinces adjacent to Attica and the Argolid. The arc spatially associates with geothermal manifestations at Lesbos and hydrothermal fields explored by research campaigns from institutions like National Observatory of Athens and universities such as University of Athens and Aristotle University of Thessaloniki.

Eruptive History and Chronology

Eruptive records combine stratigraphic sequences, tephrochronology, and historical sources from Herodotus, Pliny the Elder, and medieval chronicles tied to Venetian Republic and Ottoman Empire times. The catastrophic ~1600 BCE Thera eruption produced widespread tephra ashfall correlated with sites including Akrotiri and archaeological layers linked to the Minoan civilization and the Late Bronze Age collapse. Holocene activity includes eruptions at Kolumbo (17th century), submarine unrest near Nisyros documented in Byzantine reports, and local seismicity recorded in modern catalogs maintained by organizations like the European-Mediterranean Seismological Centre and the US Geological Survey in collaborative projects. Paleovolcanic mapping integrates results from the International Ocean Discovery Program and radiocarbon dating campaigns by laboratories at University College London and Max Planck Institute for Chemistry.

Petrology and Magmatic Processes

Magmas of the arc range from basaltic to rhyolitic compositions, showing evolution pathways recorded in phenocryst assemblages and isotopic systems (Sr-Nd-Pb) studied at institutions such as ETH Zurich and University of Cambridge. Processes include fractional crystallization, crustal assimilation, magma mixing, and volatile exsolution linked to subduction inputs from the African Plate slab and sediments of the Mediterranean Sea basin. Geochemical variations mirror patterns found in arcs like the Izu-Bonin-Mariana Arc and the Philippine Arc, with adakitic signatures and high-K calc-alkaline suites documented on islands including Milos and Santorini. Melt inclusion studies from researchers at Massachusetts Institute of Technology and Scripps Institution of Oceanography constrain pre-eruptive temperatures and volatile contents relevant to explosive potential.

Geohazards and Environmental Impact

Hazards include explosive eruptions, pyroclastic density currents exemplified by the Thera eruption, ashfall impacting ports such as Piraeus and air routes to Athens International Airport, tsunamis generated by caldera collapse or submarine landslides affecting coasts of Crete and Karpathos, and volcanic gas emissions altering local air quality near Nisyros fumaroles and hydrothermal fields. Long-term impacts influenced historical population shifts in Cyclades islands, maritime trade routes of the Byzantine Empire and Ottoman Empire, and agricultural productivity in regions like Thessaly. Risk mitigation efforts involve regional civil protection agencies of the Hellenic Republic coordinating with the European Union Civil Protection Mechanism and maritime authorities.

Monitoring and Research

Monitoring combines seismic networks by the Institute of Geodynamics (National Observatory of Athens), GPS campaigns run by the Hellenic Institute of Geodynamics, InSAR studies from the European Space Agency missions such as Sentinel-1, and marine surveys by research vessels like those of the Hellenic Centre for Marine Research and the National Oceanic and Atmospheric Administration. International collaborations include projects funded by Horizon 2020 and bilateral efforts with institutions like CNRS, GFZ German Research Centre for Geosciences, and the University of California. Ongoing research addresses eruption forecasting, submarine volcanism investigated by remotely operated vehicles linked to programs at Woods Hole Oceanographic Institution, and tephra dispersal modeling used by ICAO guidelines and regional emergency planners.

Category:Volcanism of Greece Category:Aegean Sea