Scientists say big quakes not related

By Celeste Gorrell Anstiss

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Scientists have rushed to dismiss panicked talk that the slew of recent earthquakes were connected, saying the disasters were simply nature taking its course.

Friday's magnitude 8.9 tremor in Japan - the most powerful to hit the country in 120 years - came less than a month after the devastating Christchurch quake.

A 6.1 magnitude earthquake then struck 107km south east of Tonga at 2.19pm yesterday, sending further alarm through the Pacific Island nation on tenterhooks from the tsunami warnings.

Astrologers have linked the earthquakes to the so-called "supermoon" on March 19 saying it would bring it closer to Earth than at any time since 1992, and that its gravitational pull would bring chaos.

But Canterbury University geologist Mark Quigley said the three tremors were definitely not related.

"They involve the Pacific Plate and that's about it," he said.

Quigley added a magnitude nine earthquake would hit Japan once every 120 to 150 years. Sediments from several historical tsunamis near Japan had been found as far away as the US west coast.

"Japan gets earthquakes. This is not a surprise in any way, they get magnitude seven earthquakes all the time."

All three quakes were based in the Pacific "ring of fire", one of the most volatile regions in the world.

Quigley said Tonga experienced earthquakes around 5.9 "every couple of weeks" and the theory of seismic waves being able to travel through the earth to cause movement in other faults was "at best, controversial".

Millions of Japanese were alerted to Friday's tremor a minute before it struck, thanks to the world's best early-warning system.

The sophisticated technology, connected to a network of about 1000 seismometers around the country, gave people vital seconds to take cover and was thought to have saved countless lives.

"The system functioned well because warnings were seen on television across the country," said Hirohito Naito, a seismic specialist at the Japan Meteorological Agency.

Many lessons were learned from the Kobe earthquake of 1995 that killed 6400 people and led to a reassessment of the building regulations for both residential offices and transport infrastructure.

- Additional reporting agencies

- Herald on Sunday

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