Building activity around the quake-hit province is up 34% on the previous quarter.
ASB economist Christina Leung said Statistics New Zealand data showing a 9.6% increase in construction activity nationally was above ASB and market expectations, and was driven by ''very strong activity in Canterbury''.
''We estimate construction activity in the region increased 34.1% on a seasonally-adjusted basis over the third quarter [to September], reflecting the rebuild getting well under way,'' Ms. Leung said.
Westpac senior economist Michael Gordon said the bank had been expecting national quarterly growth of 6% and the markets growth of 5.5%.
''Nationwide building activity rose sharply in the September quarter, after a subdued June quarter. The quake-hit Canterbury region was, not surprisingly, the outperformer,'' he said.
However, there were strong gains in other regions, including 7% in central Auckland and Northland, 14% in south Auckland and the Bay of Plenty and a 9% gain for Wellington.
Ms. Leung said the data showed Canterbury accounted for about half the increase in both residential and non-residential building.
She estimated residential construction activity rose 26.1% on a seasonally-adjusted basis, up from 28.4% the previous quarter.
''The rebuilding of houses is gaining further momentum, and the continued improvement in residential building consents suggest this will continue over the coming year,'' she said.