New Zealand is a globally a very seismically active country ; many quakes each year . Seismologists had predicted only a one in ten chance Tuesday 's quake would be so destructive . Seismologists for GNS Science had calculated on Monday that there was only a 35 % chance of a 5.0 magnitude aftershock hitting the region in the near future , but only a 4 % chance of a 6.0 or above aftershock . Tuesday 's second magnitude earthquake was an aftershock of a larger earthquake in September .
New Zealand is a globally a very seismically active country ; many quakes each year . Seismologists had predicted only a one in ten chance Tuesday 's quake would be so destructive . Tuesday 's second magnitude earthquake was an aftershock of a larger earthquake in September .