"For rescuers, and for this entire city, events like that are incredibly important," he said. "They raise morale and give us hope that there are others there as well."
But officials know there are limits to the human spirit and ability to survive. Traynor said 100 hours was probably the longest a trapped person could make it, given enough air and lack of injury.
"The clock is ticking," he said. "We know that."
On Wednesday, two teenage children of a local TV newscaster waited for word outside the collapsed seven-story Canterbury Television building where their mother, Donna Manning, worked and where officials fear 120 people could be under the rubble.
"My mum is superwoman, she'd do anything," one of the teens told reporters, tears streaming down her face.
Just then, a police officer approached and knelt before the family in the rain. "I have some horrible news," the officer began.