The US Geographical Survey said the quake struck 105 miles north-east of Gisborne at a depth of 19.1 miles at around 4:37am local time.A spokesman for New Zealand’s Civil Defence department said: “There is a potential tsunami threat for New Zealand following the earthquake.”People in coastal areas should stay out of the water. Stay off beaches and shore.”The National Oceanic and Atmospheric Administration has already reported “small tsunami waves” had been observed after the quake.Terrified residents reported being woken up as buildings volently shook for minutes.Chris Rawson ‏wrote: “That was one hell of an earthquake just now. Might be the longest one I’ve ever been in. Whole house shook for at least a minute.”