CHRISTCHURCH, New Zealand - A 4.5 magnitude earthquake struck New Zealand South Island city of Christchurch on Saturday evening.

The aftershock, which occurred at 7:34 pm local time (0634 GMT), was centered 10 km east of Christchurch and at a depth of 6.4 km.

Related readings:  6.3 magnitued earthquake hits S New Zealand

Xinhua reporter in Christchurch said the aftershock caused houses to rattle. The aftershock lasted about seven to 10 seconds.

The second biggest aftershock on Saturday struck at 10:49 am and measured 4.1 on the Richter scale. It was centered 10 km west of Lyttelton at a depth of 5 km.

There have been more than nine aftershocks in Christchurch on Saturday, ending an aftershock-free period of 14 hours.

The ground has been shaking much of Saturday.

All the aftershocks on Saturday before 8 pm were centered between 10 and 20 km from Lyttelton at depths ranging from 2 to 6 km.

In chronological order, their magnitudes have been 3.2 (at 12: 52 am), 3.4 (at 6:14 am), 3.3 (10:04 am), 4.1 (10:49 am), 3.2 (11:17 am), 3.4 (1:19 pm), 3.5 (2:29 pm) and 4.5 (7:34 pm).

A 6.3 magnitude earthquake struck Christchurch on Feb 22, with the official death toll standing at 165 on Friday.