Tomographic imaging of the NW edge of the Hellenic volcanic arc

• DOI: 10.1007/s10950-019-09849-8
• Publication Date: 2019-06-28T11:02:57Z
• Authors: Andreas Karakonst...; Panayotis Papadim...; Christos Millas; Ioannis Spingos; Ioannis Fountoulakis; George Kaviris
• Keywords: Eurasian Plate; Clockwise; Seismic Tomography; Focal mechanism; Classification of discontinuities

The broader South Aegean area is characterized by the convergence of the African and Eurasian lithospheric tectonic plates at a rate of approximately 30 mm/year, resulting in a complex and intense deformation of the Aegean (McClusky et al. Geophys. Res. 105: 5695–5719, 2000). The Saronikos Gulf, situated in the NW termination of the Hellenic volcanic arc (Central Aegean Sea), is an area of special geophysical interest due to the variety of the recorded seismicity, regarding both the origin (tectonic, volcanic) and the focal depths. The presence of Plio-Quaternary volcanic centers and the complex seismicity distribution urge the need of detailed research on the geophysical properties such as seismic velocities, revealing possible presence of magmatic bodies or geothermal fluids. In the present study, more than 3000 manually revised events were located using a local 1-D layered velocity model. The main spatiotemporal clusters are concentrated along the Leuces and Methana-Poros E-W striking neotectonic fault zones. A local earthquake tomography (LET) was performed, using body-wave (P and S) travel time data, to investigate small to medium scale (~ 10 km) anomalies that can be related to local neotectonic or volcanic patterns. Major shallow ~ E-W to NW-SE trending discontinuities between positive (to the north) and negative (to the south) VP perturbations, anticorrelated to the respective VS image, are identified south of Aigina Island. These results are mainly related to the principal local stress orientation and fault zones (~ E-W to NW-SE strike), such as the Moni, Anghistri, and Leuces, whereas the respective Vp/Vs ratio values imply the presence of possible magmatic features which can be linked to the Plio-Quaternary NW edge of the Hellenic volcanic arc and hydrothermal activity ENE of Poros Island.