Life in parts of New Zealand's earthquake-hit city of Christchurch has begun to return to normal. But a sharp series of aftershocks sent more people to shelters.

The city center remained cordoned off by troops Tuesday. Only building owners and workers were allowed in to begin clearing up the mess.

The public transport service has resumed and some shops, reopened. Overnight, about 20 shocks, including two of magnitude 5.4, rattled the city. Quake experts say aftershocks likely will continue for several weeks.