Normal faulting around Kolumbo Volcano – exploring relationships between stress fields and volcanism

The Christiana-Santorini-Kolumbo volcanic field, in the Aegean Sea, has hosted more than 200 explosive eruptions in the past 360,000 years, including the 1650 eruption of Kolumbo Volcano. In this contribution, we use the first 3D seismic reflection data collected over the submarine Kolumbo Volcano to explore active faulting and its relationship to volcanism. The 3D data enable us to extract useful fault attributes (strike, dip, dip direction) which can be used to decipher local stress fields. Our results reveal clear NW-SE directed extension around the volcano, consistent with published focal mechanisms from microseismicity. The data also provide exceptional 3D imaging of the Kolumbo Fault Zone, which lies ~6 km northwest of Kolumbo Volcano. Interpreted horizons through the Kolumbo Fault Zone reveal distinct relay ramps between overstepping normal faults. We suggest that magma ascent within the fault zone likely exploits enhanced vertical permeability associated with distributed deformation within relay ramps. Further research is required to understand the range of scales over which relay ramps could affect crustal permeability, and by inference magma ascent, in the greater rift zone.