The 14 February 2008 earthquake (M6.7) sequence offshore south Peloponnese (Greece): Source models of the three strongest events

We investigate the rupture process of the strongest events of the 14 February 2008 sequence which ruptured ~ 30 km of the western Hellenic trench. Three were the strongest events of the sequence: the first one (M6.7) occurred on 14 February 2008 at a depth of ~ 30 km, on a low-angle (10°) thrust fault, followed within 2 h by an M6.1 aftershock at a depth of ~ 33 km, also on a low-angle thrust fault and the third one on 20 Feb 2008 of M6.0 which is characterized as a strike-slip event at shallower depth (~ 10 km). We used the M6.1 aftershock as empirical Green's function (EGF) to invert for the slip distribution of the strongest M6.7 event of the sequence. We were able to identify the low-angle plane (strike 288°, dip 10° and rake 73°) as the fault plane. The slip model is dominated by two distinct slip patches, which extend towards SSE from the hypocenter, thus implying rupture directivity toward the island of Crete, a result which is further supported by our teleseismic waveform inversion results. Maximum slip is estimated at ~ 270 cm, while average slip on the ruptured area (area of subfaults of non-zero slip) was ~ 70 cm. Most of the slip (> 95% of total) is confined in an area of 34 × 22 km2. We attribute the occurrence of the shallow strike-slip event, just above the interplate thrusting at depth, to slip partitioning, due to the deflection of slip vectors from the expected plate convergence vector.