An international team of scientists has completed the second phase of the largest marine geophysical survey ever conducted in Greek waters, gathering new data on the fault systems responsible for some of the Mediterranean's most powerful earthquakes.
The expedition, known as ODISSEY, mapped active geological structures beneath the Ionian Sea west of Corfu, Kefalonia, Zakynthos and the Peloponnese, one of Europe's most seismically active regions.
Researchers recorded more than 2,200 kilometers of high-resolution seismic reflection profiles, creating what organizers describe as one of the most comprehensive marine geophysical datasets ever compiled in Greece.
The survey was led jointly by Spain's Institute of Marine Sciences (ICM-CSIC), under Dr. Manel Prada, and the National and Kapodistrian University of Athens, under Prof. Evi Nomikou. Prof. Nomikou said the region "has produced some of the strongest earthquakes in the Mediterranean," underscoring the need to understand its active faults.
Researchers used a system of 18 airguns and a three-kilometer streamer equipped with 240 hydrophones to image geological formations at depth, data that could improve tsunami-risk assessments and models of how energy is released along fault lines during earthquakes.
During the survey's first phase, teams deployed 18 underwater seismometers that will remain on the seabed for a year, continuously recording seismic activity, including tremors too small to be felt on the surface.
A third phase, scheduled for the coming days, will add 17 more seismometers, allowing scientists to build a three-dimensional seismic tomography model of the region.
Greek participation was extensive, with University of Athens researchers including Dr. Spyridon Dilalos and doctoral candidates Sotiria Kothri, Amalia-Georgia Papazoi and Anna Katsigera taking part alongside graduate students.
The mission also involved Italy's ISMAR, Germany's GEOMAR, Greece's Hellenic Hydrocarbon Resources Management Company, and the Hellenic Navy's Hydrographic Service, aboard the Spanish research vessel R/V Sarmiento de Gamboa.
Findings are expected to inform Greece's Civil Protection Ministry in updating earthquake and tsunami risk models for the country's western coastline.
By Vassilis Goulas