Civil defence officials fear Wednesday night's earthquake could trigger the big one that's overdue for southern New Zealand.
And they're warning people not to become complacent, just because this week's quake didn't cause much damage.
Geologists say that most of the energy from the 7.8 Fiordland quake dissipated into soft rocks to the west.
Canterbury University earthquake expert Mark Quigley says the fact that the aftershocks - 13 of them by 7pm Friday - have not ruptured the onshore alpine fault could actually put more stress on it.
Dr Quigley says magnitude 8 earthquakes occur every 200-300 years and the last one was registered in 1717, so the next one is overdue.
The chief executive of Environment Southland, Ciaran Keogh, is one of several local-government officials concerned that the lack of damage will paint an unrealistic picture of the havoc the big one could cause.
New Zealand Civil Defence director John Hamilton says it's a timely reminder for people to be prepared, as it's a matter of when, not if, a major emergency occurs.
Claims, mostly for minor damage, flooding in
Meanwhile, claims for damage compensation are flooding into the Earthquake Commission, which predicts the final number could be several thousand, collectively topping $4 million.
By early Friday afternoon, more than 400 claims - mostly for minor damage - had been lodged. Wall and ceiling cracks and shattered windows are the main problems.
Most of the claims are from Southland, followed by Dunedin and Queenstown, but they come from as far north as Tasman.