Aftershocks slowly tapering off

Photo / Mark Mitchell

Despite a flurry of aftershocks over the past 24 hours, a GNS Science seismologist maintains the aftershocks are dying down.

Three more aftershocks this morning followed five yesterday, according to GeoNet. The largest was a 4.6-magnitude aftershock 20km west of Christchurch at 12.30am yesterday, which had been the first tremor since Saturday night.

"It is tailing off. They don't get smaller in a hurry. They do get less frequent and that's what we're seeing," said GNS Science seismologist Warwick Smith.

"It is a long process, we said that at the outset."

Mr Smith said it may be a week or two before the aftershocks cease, with aftershocks coming and going.

Experts initially suggested the main magnitude-7.1 quake on September 4 would be followed by an aftershock measuring about 6 on the Richter scale.

However, the chance of that was now looking less likely, Dr Smith told Radio New Zealand.

"About 20 minutes after the main shock two weeks ago there was a 5.6 and it is indeed beginning to look as though that might turn out to be the largest aftershock," he said.

Christchurch's central city remained blocked off at the weekend, and the Army was called in to help patrol cordons after police arrested seven people breaching them.

- NZPA and NZHERALD STAFF