A week after the devastating shallow earthquake that struck Christchurch, New Zealand, on Feb. 22, structural engineers are surprised and relieved that damage to modern engineered buildings was not even more widespread. Recordings at several instrumented sites indicated that ground motion exceeded the maximum considered event. The MCE has a one in 2,500 chance of happening in any given year.
The magnitude-6.3 Canterbury quake, centered some 10 kilometers from downtown Christchurch and only 5 km deep, caused significantly more damage than the magnitude-7.1 quake that struck the area on Sept. 4, 2010.