Los Angeles County firefighters are among the hundreds of search and rescue workers at the scene.
Seventy people were pulled from the rubble the first day after the earthquake, but no one has been found alive since.
The death toll stands at 145.
Thousands are without water and power and many homes are no longer safe. Many have been forced to sleep in their cars or tents as their unstable houses sway with the relentless aftershocks.
Christchurch Mayor Bob Parker said 780 portable toilets have been installed throughout the city of 350,000, and hundreds more are on their way.
Though survivors are dealing with miserable conditions, one woman who was pulled from the rubble has found happiness.
Three days after being rescued, Emma Howard got married.
She almost didn't make it to her wedding day.
Tuesday's earthquake caused her office building to collapse, trapping her for more than six hours.
Howard used a cell phone to let her fiancé know she was okay.
"I got this text ... saying 'It's Emma here. I'm OK and I love you very much," said Chris Greenslade, who was outside his office across town when the disaster struck Tuesday afternoon and raced to find Howard.
Howard, 23, escaped with only minor scratches.
The couple says going ahead with the wedding is their way of showing that a disaster cannot break people's spirits.
The Associated Press contributed to this report.