NEWS RELEASE, 22 AUGUST 2001
TUESDAY'S QUAKE BIGGEST IN SIX YEARS

Tuesday's magnitude 7.0 earthquake 420km northeast of Gisborne was New Zealand's
biggest jolt since a magnitude 7.1 earthquake struck in a similar location on 6
February 1995.

The Institute of Geological & Nuclear Sciences Limited (GNS) said there had been
more than 130 aftershocks, mostly between magnitude 3 and 5, since the quake
struck at 6.52pm on Tuesday. The focal point of the main shock was 33km deep.
Tremors were felt from Auckland to Otago, but most strongly along the North
Island's east coast.

The earthquake was centred at the southern end of the Tonga-Kermadec subduction
zone ? the world's busiest area for deep earthquakes, GNS seismologist Terry
Webb said.

" It's fortunate that it was centred so far from land. If it had been closer to
shore, or near a population centre, we would have been talking about serious
damage and possibly casualties," Dr Webb said.

The most likely cause of the earthquake was the bending of the Pacific plate as
it sinks beneath the Australian plate to the east of New Zealand.

" We would expect an earthquake of this magnitude to occur on-land in New
Zealand once every decade, so it's quite an unusual event."

Dr Webb said the earthquake released about 30 times more energy than the atomic
bomb dropped on Hiroshima at the end of World War 2.

" As with all large earthquakes, it was detected by seismic instruments
globally."

It was unlikely that the earthquake had relieved the stress on any of New
Zealand's major active faults as it was too far away.

Dr Webb noted that amateur meteorologist Harry Alcock of Hamilton had last week
predicted New Zealand would be affected by a large earthquake because of the
Moon's proximity to the Earth.

" We're not aware of any scientific literature confirming that the Moon is able
to trigger earthquakes, although scientists have investigated this. It would be
really exciting if a breakthrough occurred in an area such as this."

Dr Webb suggested that Mr Alcock should document his observations and have them
reviewed by scientists.

" Testing ideas is how science advances. The science community would welcome the
opportunity to evaluate such a hypothesis if the facts were laid out before us.

" Over the past 50 years many people have tried unsuccessfully to predict
earthquakes. Any prediction technique needs to have a solid track record of
successes before it can be taken seriously."

Dr Webb said false predictions had the potential to cause panic and could end up
causing as much disruption as an earthquake itself.

He said that earthquake activity in New Zealand had been "quieter than the
long-term average" during the past 50 years.

" The number of big on-land earthquakes since the early 1940s gives a misleading
impression about the earthquake hazard we face. New Zealand won't stay in this
relatively quiet state indefinitely, so it makes sense to be prepared for a
damaging earthquake.

" Tuesday's earthquake is a reminder that we live in one of the world's more
seismically active countries."

END