The triggering event of systematization in Bucharest was the major earthquake of 1977, which predominantly struck edifices built before World War II (preceded by another major earthquake, that of November 10, 1940), while the structures dating from the communist era held out well. This was interpreted by the communist regime as a proof of its superiority over the pre-war regimes, and led to a paradigm change in its urban development policy. Up to that time, the communist regime had concentrated on the clearance and redevelopment of slums like "Groapa Floreasca" or "Groapa lui Ouatu" (1950s) as well as on new high-density urban settlements in the suburbs, such as "Bucureștii Noi" (1950s), "Balta Albă (later "Titan"), "Berceni", "Giurgiului" or "Drumul Taberei" (1960s), while the city remained basically untouched. The impacts of the earthquake, more severe in the central city, provided both ideological and technical arguments for urban intervention in historical Bucharest.