He had been taking part in an international paediatric medicine conference on the 14th floor of the Grand Chancellor Hotel when the quake occurred shortly before 1pm.
He praised hotel staff for their rapid response in evacuating guests from the 24-storey hotel via the stairs.
Dr Chambers and other doctors attending the conference pitched in to help deal with casualties.
Immediately after he had left the hotel he had found the situation "very frightening" with masonry falling from nearby buildings.
He helped undertake triage work, assessing casualties, at two locations throughout the night, working until 10am on Wednesday.
Dr Chambers was impressed by the high level of skills shown by Christchurch doctors and other medical colleagues.
The Grand Chancellor Hotel, the tallest building in Christchurch, remains empty and there are growing fears it will collapse.
On Thursday night, Dr Chambers attended a function in his honour, attended by about 50 people, to celebrate his 17 years as Dunedin Hospital's emergency department clinical leader.
Dr Chambers, who continues to work as a specialist in the department, apologised for not preparing a formal speech.
He had been "rattled" by the earthquake, he said.
Nevertheless, he discussed some of his most moving experiences, including helping save the life of a 4-year-old child with a rare heart condition.
