[1] Aristotle Univ Thessaloniki, Sch Geol, Dept Geophys, Thessaloniki 54124, Greece
[2] Univ Montpellier, Dept Geosci, F-34095 Montpellier, France
[3] CNRS, F-34095 Montpellier, France
[4] Aristotle Univ Thessaloniki, Sch Phys, Dept Appl & Environm Phys, Thessaloniki 54124, Greece
[5] NCSR Demokritos, Inst Nanosci & Nanotechnol, Athens 15310, Greece
[6] Aix Marseille Univ, CNRS, CCJ, Aix En Provence, France