The Japan quake was 8000 times stronger than Christchurch's and unzipped a faultline half the size of the North Island, a NZ scientist says.

Christchurch Mayor Bob Parker says the thoughts of his quake-stricken city are with Japan following Friday's magnitude 9.0 earthquake which devastated much of the country and left thousands dead.

Japanese officials have confirmed a second hydrogen explosion has occurred at the Fukushima Daiichi nuclear power plant, while a warning of a second tsunami has been cancelled.

Japanese officials warned of a possible second explosion at a nuclear plant crippled by the earthquake and tsunami as they raced to stave off multiple reactor meltdowns, but they provided few details about whether they were making progress.

Three nuclear power plants in Japan have suffered failure, with a top Government official warning a meltdown at one of the plants was "highly possible". Over 10,000 people are thought to be missing as officials fight to avoid a catastrope

The family of a NZ man in Japan have heard nothing from him since hours before the deadly quake and tsunmai which struck on Friday night

Read the latest accounts from people around the world via Facebook and Twitter.

The Robinson family of Nelson breathed a huge sigh of relief this morning when they finally reached their daughter in Japan.

A compilation of some of the most remarkable video to emerge from Friday night's disaster in Japan

It is starting to feel like elements of Hiroshima, Kobe and the Asian tsunami combined.

Kiwis' nerves fray after a tsunami alert and an earthquake off Tonga.