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We have employed the data of EGELADOS temporary network (October 2005-April 2007) to determine 88 focal mechanism solutions from Southern Aegean Sea using the RAPIDINV algorithm (Cesca et al., 2010). The new focal mechanism solutions determined, complemented with the previously available ones for Southern Aegean Seα provide the basis for a detailed examination of the stress field, using the distribution of P and T axes. To obtain the stress field we applied the method of Gephart and Forsyth (1984), namely the grid search inversion approach of Gephart (1990a,b), which incorporates the P and T axes of selected focal mechanisms. For the inversion, the initial stress solutions were computed by the “average” kinematic P and T-axis approach of Papazachos and Kiratzi (1992). The stress-inversion allows choosing the "ideal" fault plane corresponding to the minimum misfit rotation about an axis of general orientation which is needed to match an observed fault plane/slip direction with one consistent with the final stress model.

We employ the stochastic finite‐fault modeling approach of Motazedian and Atkinson (2005), as adapted by Boore (2009), for the simulation of Fourier amplitude spectra (FAS) of intermediate‐depth earthquakes in the southern Aegean Sea subduction (southern Greece). To calibrate the necessary model parameters of the stochastic finite‐fault method, we used waveform data from both acceleration and broadband‐velocity sensor instruments for intermediate‐depth earthquakes (depths ∼45–140  km) with M 4.5–6.7 that occurred along the southern Aegean Sea Wadati–Benioff zone. The anelastic attenuation parameters employed for the simulations were adapted from recent studies, suggesting large back‐arc to fore‐arc attenuation differences. High‐frequency spectral slopes (kappa values) were constrained from the analysis of a large number of earthquakes from the high‐density EGELADOS (Exploring the Geodynamics of Subducted Lithosphere Using an Amphibian Deployment of Seismographs) temporary network. Because of the lack of site‐specific information, generic site amplification functions available for the Aegean Sea region were adopted. Using the previous source, path, and site‐effect constraints, we solved for the stress‐parameter values by a trial‐and‐error approach, in an attempt to fit the FAS of the available intermediate‐depth earthquake waveforms. Despite the fact that most source, path, and site model parameters are based on independent studies and a single source parameter (stress parameter) is optimized, an excellent comparison between observations and simulations is found for both peak ground acceleration (PGA) and peak ground velocity (PGV), as well as for FAS values. The final stress‐parameter values increase with moment magnitude, reaching large values (>300  bars) for events M≥6.0. Blind tests for an event not used for the model calibration verify the good agreement of the simulated and observed ground motions for both back‐arc and along‐arc stations. The results suggest that the employed approach can be efficiently used for the modeling of large historical intermediate‐depth earthquakes, as well as for seismic hazard assessment for similar intermediate‐depth events in the southern Aegean Sea area.

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