Slab stress field in the Hellenic subduction zone as inferred from intermediate-depth earthquakes

The stress regime across the Hellenic subduction zone was investigated by performing stress inversion on 100 intermediate-depth moment tensor solutions. In this study, the slab was divided into four sectors based on earthquake distribution, trench geometry, and the results of a previous study of slab geometry. For the Peloponnese sector, moment tensors reaching 80 km depth were inverted, and the slab stresses were compatible with a possible slab tear. For the Kithira-Western Crete and Crete sectors, homogeneity was observed at depths up to 100 and 80 km, respectively. For these two areas, the subvertical σ₃ and along-strike σ₁ justify slab rollback as the driving mechanism. The differences in the stress regime and azimuth of the maximum compression of these two sectors may reflect a bulge in the slab. For the fourth sector, Karpathos-Rhodes, two distinct subsectors were defined along a depth gradient (50-90 km and 90-180 km, respectively). The strong heterogeneity observed at both depths and changes in the stress regime from slab pull to extension may be an indication of a double WadatiBenioff zone. The membrane strain model presented here can provide a possible explanation for the along-strike compression observed at the top 90 km in three of the four sectors.