Although not as powerful as the magnitude 7.1 earthquake on 4 September 2010, this earthquake occurred on a faultline that was shallow and close to the city, so the shaking was particularly destructive. In the February 2011 quake, the fault movement and structure of the bedrock produced exceptionally strong ground motion – up to 1.8 times the acceleration due to gravity in the eastern suburbs. In the city centre ground accelerations were three to four times greater than the ground motion produced by the September 2010 earthquake.