Tsunami warning after 7.8 quake 800km north of New Zealand

by Sail-World.com on 7 Jul 2011 The New Zealand Ministry of Civil Defence and Emergency Management (MCDEM) this morning issued a tsunami warning, later withdrawn after a powerful 7.6 earthquake struck off the Kermadec Islands, 800km north of New Zealand. However a marine surge warning remains.

Kermadec Island Earthquake information Magnitude 7.6

Wednesday, July 06, 2011 at 19:03:16 UTC
NZL time Thursday, July 07, 2011 at 07:03:16 AM at epicenter

Location 29.312°S, 176.204°W Depth 20 km (12.4 miles)

Distances
161 km (100 miles) E (93°) from Raoul Island, Kermadec Islands
913 km (567 miles) S (186°) from NUKU'ALOFA, Tonga
3007 km (1868 miles) WSW (239°) from PAPEETE, Tahiti, French Polynesia

There was an initial tsunami advisory warning issued for the Pacific - for the Kermadec Islands, Tonga and New Zealand based on the size of the quake.

Radio New Zealand reported that Pacific Tsunami Warning Centre geophysicist Victor Sardina said a tsunami had been generated, with a buoy off Raoul Island registering a 60cm high tsunami.

However in a fast moving process the Pacific Tsunami Warning withdrew the warning, however Civil Defence New Zealand did not until almost an hour later.

The New Zealand Civil Defence agrees there were mixed messages with this morning's tsunami warning following this morning's 7.6 magnitude earthquake off the Kermadec Islands.

The Pacific Tsunami Warning Centre issued and cancelled its tsunami warnings before the Civil Defence, however the PTWC warnings do not have official status for New Zealand.

Civil Defence operations manager David Coetzee agreed there were mixed messages as to the warning situation this morning. 'I appreciate it can be pretty confusing,' he confirmed.

He told Radio New Zealand this morning that Civil Defence bases its decisions on GNS Science advice.

The tsunami warning was cancelled by Civil Defence just after 9am.

Coetzee said. 'When earthquakes of a certain magnitude occur within a certain area at a certain depth then we start doing things as a matter of process. And we assess the threat from there on and we either upscale or downscale [the threat], whatever we need to do.

'But we can't wait until a proper, more confident assessment has been made - we need to act fast and in this case particularly (as a tsunami would only have) two to three hours travel time from the Kermadecs to the first New Zealand coast.

'We take the precautionary route and do what we have to do.'

Coetzee said the marine threat was 'all the down the east coast to Hawkes Bay.'

His advice was to stay out of the water all day, with a strong current likely and unpredictable turbulence in the water. Any surge could be up to one metre but 'probably around 60cm was a calculated guess.'

'My advice is to stay out of the water all day.'