A shallow 5.0-magnitude aftershock rocked the quake-hit New Zealand city of Christchurch today, shaking items off shelves. The US Geological Survey said the quake hit at 9:09 am local time was centred 22 kilometres west of the city at a depth of just three kilometers. New Zealand's GNS Science said the quake caused only minor damage. GNS Science said Christchurch was also hit by another smaller aftershock, measuring 3.7, about an hour before the 5.0 tremor. New Zealand's second largest city was devastated by a 6.3-magnitude earthquake in February which claimed 181 lives.