However, GNS Science later revised the magnitude down and updated its location to 30km west of Arthur's Pass.
The quakes had caused no infrastructure damage. More than 3000 people from Mandeville in Southland to the central North Island reported feeling the quake.
Seventeen insurance claims had so far been lodged with the Earthquake Commission, mostly from residents in the Christchurch and Canterbury areas, a spokeswoman said.
Among those shaken by the quakes was Kiwi actress and former partner of Sam Neill, Lisa Harrow, who said she was lying awake in her Port Levy home about 6.30am when she felt the quake hit.