Christchurch shaking again

Two aftershocks have struck 20km west of Christchurch this morning, GNS Science is reporting.

The first, a 4.1 magnitude quake, hit at 9.40am at a depth of 10km and was reportedly felt in the Christchurch area.

It was followed shortly by a quake measuring 3.6 on the Richter scale at 9.41am, at a depth of 15km.

The Christchurch City Council is reminding people to take care in the central city, where around 4km of cordons are still in place following the Boxing Day aftershocks.

More than 3000 buildings have been assessed externally this week, with 151 requiring immediate remedial work.

Due to the number of cordons in place in the central city, a 30km/h speed restriction still exists in some central city streets.

The restriction is in place in the area bounded by St Asaph, Madras and Gloucester streets and Cambridge Tce/Durham Street.