WELLINGTON -- A severe earthquake rocked south island of New Zealand right after Sunday midnight, according to an announcement the country's Geonet posted on its website.

Geonet said the quake with magnitude on richer scale of 7.6 struck at 12:02:56 am on Sunday local time with a depth of 16km. It was later revised at 6.6 followed by a series of moderate aftershocks both in south and north island.

The epicenter of quake is located at 15km southeast of Hanmer Spring, a hot spring tourist town some 130 northwest of Christchurch, the biggest city of south island.