In New Zealand, the residents of the quake-hit Christchurch have been told to prepare for a hard grind ahead as strong aftershocks continue to shake the second biggest city. The aftershocks have been as strong as magnitude 5.0 and the city centre will remain closed tomorrow. However, the business owners will be allowed in to assess the damage to their property. According to reports, about 500 buildings have been destroyed and authorities have ordered the city's schools to stay closed until Wednesday as engineers carry out structural checks. Prime minister John Key has said rebuilding Christchurch could take a year because many buildings will have to be knocked down. Despite the widespread damage no-one was killed by the earthquake but two people were seriously injured and another died of a heart attack during the disaster. The powerful 7.0-magnitude earthquake struck the city in the early morning hours yesterday.