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 .
New Zealand is a globally a very seismically active area ; 15,000 quakes each year . Seismologists had predicted only a one in twenty chance Tuesday 's quake would be so destructive . Christchurch 's 6.3 magnitude quake was an aftershock of a larger earthquake in September .