New Zealand warned to brace for more damage as aftershocks set to keep hitting
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Pastor Dale Morgan
Feb 26, 2011, 3:01:52 AM2/26/11
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Great
Earthquakes In Diverse Places
New Zealand warned to brace for more damage as aftershocks set to keep hitting
* By Doug Conway
* From: The Courier-Mail
* February 26, 2011 12:00AM
New Zealand Earthquake
A NSW Fire Rescue team help search the Pyne Gould Corporation building in the CBD of Christchurch.
The 6.3 magnitude earthquake has left hundreds dead and destroyed much of the city
Crews continue sifting through the destroyed CTV building in Christchurch as the death toll grows
* Experts warn aftershocks will continue for a year
* Tremors will become "less frequent and smaller"
* Fears over landmark building collapse
CHRISTCHURCH can expect further earthquake aftershocks for a year, and Wellington faces a higher risk of a bigger quake, an Australian seismologist has warned.
Devastated Christchurch
Christchurch faces a long road to recovery after its devastating earthquake, as John Ferguson reports.
"I think there will be lots of aftershocks around Christchurch for about a year," said Kevin McCue, director of the privately owned Australian Seismological Centre.
"But they won't be as big as the latest one. They are likely to get smaller and less frequent."
It comes as authorities concede it is unlikely they will find any more survivors from Christchurch's devastating earthquake. The death toll stands at 123 and is expected to rise further today. More than 200 people are still listed as missing.
The Canberra-based seismologist said the biggest surprise about Tuesday's 6.3-magnitude aftershock in Christchurch was that it took so long after a powerful quake last September, which caused no fatalities but weakened many buildings.
"I expected it within the first four or five days," he said.
He said the worrying thing was that the aftershock occurred so much closer to the city of 340,000 than last year's quake, which was centred up to 50km away.
But some Australian and New Zealand seismologists are in dispute over whether the Christchurch earthquake was a September aftershock or an unrelated quake.
Geoscience Australia seismologist Dr Trevor Allen said Tuesday's event happened in a different fault line.
"We say that if it happens on a different fault line or a different section of the same fault line, then it is its own earthquake," Dr Allen said.
He said aftershocks were generally around the same depth as the original earthquake but Tuesday's brutal quake was shallow - 5km below the surface.
The shallowness of the quake also led to significant liquefaction in Christchurch, where the soil "liquefies" and is pushed to the surface.
Fellow seismologist David Jepsen said there was no connection between the Christchurch quake and earthquakes in other parts of the world, with more than 25 tremors recorded in the Pacific "ring of fire" in the past week.
"Although an earthquake's destructive forces can be immense, energy released is relatively localised on a global scale," he said.
A New Zealand-based geologist believes the strength of the earthquake, which left much of Christchurch in rubble on Tuesday, may have been magnified as it reflected off hard volcanic rock below its epicentre.
GNS Science earthquake geologist Kelvin Berryman said: "With the epicentre of Tuesday's earthquake in the Port Hills, a large amount of energy could have been reflected off hard volcanic rock at depth.
"This would have compounded the impact of the earthquake at the surface."
But the big question for New Zealand was what impact it would have on the boundary between the Australian and Pacific tectonic plates, which runs up the west coast of the south island, across Cook Strait, under Wellington and up the east coast of the North Island.
"It's got to have some impact," Mr McCue said.
New Zealand's reputation as the "shaky isles" springs from its location near the bottom of the 40,000km seismic horseshoe known as the Pacific "ring of fire".
The ring, fired by the movement of the plates that make up the Earth's crust, embraces 452 volcanoes and is home to 90 per cent of all earthquakes and 80 per cent of the largest ones.
Mount Ruapehu, one of New Zealand's most active volcanoes in the centre of the North Island, had its last spectacular eruption in 1995-96.
New Zealand warned to brace for more damage as aftershocks set to keep hitting
* By Doug Conway
* From: The Courier-Mail
* February 26, 2011 12:00AM
New Zealand Earthquake
A NSW Fire Rescue team help search the Pyne Gould Corporation building in the CBD of Christchurch.
The 6.3 magnitude earthquake has left hundreds dead and destroyed much of the city
Crews continue sifting through the destroyed CTV building in Christchurch as the death toll grows
* Experts warn aftershocks will continue for a year
* Tremors will become "less frequent and smaller"
* Fears over landmark building collapse
CHRISTCHURCH can expect further earthquake aftershocks for a year, and Wellington faces a higher risk of a bigger quake, an Australian seismologist has warned.
Devastated Christchurch
Christchurch faces a long road to recovery after its devastating earthquake, as John Ferguson reports.
"I think there will be lots of aftershocks around Christchurch for about a year," said Kevin McCue, director of the privately owned Australian Seismological Centre.
"But they won't be as big as the latest one. They are likely to get smaller and less frequent."
It comes as authorities concede it is unlikely they will find any more survivors from Christchurch's devastating earthquake. The death toll stands at 123 and is expected to rise further today. More than 200 people are still listed as missing.
The Canberra-based seismologist said the biggest surprise about Tuesday's 6.3-magnitude aftershock in Christchurch was that it took so long after a powerful quake last September, which caused no fatalities but weakened many buildings.
"I expected it within the first four or five days," he said.
He said the worrying thing was that the aftershock occurred so much closer to the city of 340,000 than last year's quake, which was centred up to 50km away.
But some Australian and New Zealand seismologists are in dispute over whether the Christchurch earthquake was a September aftershock or an unrelated quake.
Geoscience Australia seismologist Dr Trevor Allen said Tuesday's event happened in a different fault line.
"We say that if it happens on a different fault line or a different section of the same fault line, then it is its own earthquake," Dr Allen said.
He said aftershocks were generally around the same depth as the original earthquake but Tuesday's brutal quake was shallow - 5km below the surface.
The shallowness of the quake also led to significant liquefaction in Christchurch, where the soil "liquefies" and is pushed to the surface.
Fellow seismologist David Jepsen said there was no connection between the Christchurch quake and earthquakes in other parts of the world, with more than 25 tremors recorded in the Pacific "ring of fire" in the past week.
"Although an earthquake's destructive forces can be immense, energy released is relatively localised on a global scale," he said.
A New Zealand-based geologist believes the strength of the earthquake, which left much of Christchurch in rubble on Tuesday, may have been magnified as it reflected off hard volcanic rock below its epicentre.
GNS Science earthquake geologist Kelvin Berryman said: "With the epicentre of Tuesday's earthquake in the Port Hills, a large amount of energy could have been reflected off hard volcanic rock at depth.
"This would have compounded the impact of the earthquake at the surface."
But the big question for New Zealand was what impact it would have on the boundary between the Australian and Pacific tectonic plates, which runs up the west coast of the south island, across Cook Strait, under Wellington and up the east coast of the North Island.
"It's got to have some impact," Mr McCue said.
New Zealand's reputation as the "shaky isles" springs from its location near the bottom of the 40,000km seismic horseshoe known as the Pacific "ring of fire".
The ring, fired by the movement of the plates that make up the Earth's crust, embraces 452 volcanoes and is home to 90 per cent of all earthquakes and 80 per cent of the largest ones.
Mount Ruapehu, one of New Zealand's most active volcanoes in the centre of the North Island, had its last spectacular eruption in 1995-96.
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