Aftershocks are continuing to rattle New Zealand after a 7.5-magnitude earthquake led to two deaths and caused widespread damage.
Four tremors of severe intensity measuring between 5.6 and 5.8 were felt in a 40-minute period on Monday night. There have been no reports of damage.
Three were located east or south-east of the Marlborough town of Seddon, while one was east of Kaikoura, which is already cut off to the north and the south.
They were among a host of aftershocks above 5, the highest so far being a 6.3 shake, since the initial earthquake struck just after midnight on Monday.
Dr Mark Quigley, from the University of Melbourne, says that, for an earthquake of magnitude 7.5 to 7.8, several large aftershocks (greater than 6) are expected.
"For each magnitude 6 aftershock, we expect 10 more magnitude 5 aftershocks over the coming days and weeks," he said.
Dr Quigley, who is Associate Professor in active tectonics and geomorphology at the university's School of Earth Sciences, said the region had been one of the most seismically active in the New Zealand over the past few years.
