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Rifting and rises are prominent landscape features in the roughly triangular area characterized by the presence of three major rises (Atla, Beta and Themis) and two corona-dominated long chasmata (Hecate and Parga). The coronae population associated with these chasmata represents 35% of all Venusian coronae and 56% of coronae associated with fracture zones (Smrekar et al., 2010). We focused on the spatial analysis of the coronae population associated with Parga chasma for identifying the depth of the main thermal anomaly that fed (and maybe still feeds) them. We explore a formation mechanism for coronae based on the Rayleigh-Taylor (RT) gravitational instability (Tackley and Stevenson, 1991) of the lithosphere that may occur when a layer of dense fluid overlies a layer of less dense fluid. The RT gravitational instability theory can be used to draw a relationship between the spacing of volcanic …