Quake links investigated

Palmerston North resident Jason Holding talks about the earthquake and coming outside to see the front fence had fallen down.
Palmerston North resident Jason Holding talks about the earthquake and coming outside to see the front fence had fallen down.
The fire service assists residents in McGriffert Street Palmerston North after an earthquake in the Manawatu and Wairarapa regions today.
The fire service assists residents in McGriffert Street Palmerston North after an earthquake in the Manawatu and Wairarapa regions today.
Earthquake in palmerston north. Fixing Katrina Nicholson's chimney on McGriffert St.
Earthquake in palmerston north. Fixing Katrina Nicholson's chimney on McGriffert St.
Earthquake. Buses replace trains after the earthquake. Signs at the railway station advise of the change.
Earthquake. Buses replace trains after the earthquake. Signs at the railway station advise of the change.
The road to Pongaroa, in the Tararua District.
The road to Pongaroa, in the Tararua District.
Kitchen left a mess in Eketahuna.
Kitchen left a mess in Eketahuna.
Donna Isaacson's shed in Ashhurst a little worse for wear after the earthquake.
Donna Isaacson's shed in Ashhurst a little worse for wear after the earthquake.
Crack in the road of Apollo Parade, Palmerston North.
Crack in the road of Apollo Parade, Palmerston North.
The rockfall at Castlepoint.
The rockfall at Castlepoint.
Damaged power poles.
Damaged power poles.
Ricky Gray's TV was badly damaged in the quake. "[I] Could hear the quake coming about twenty seconds before I felt it."
Ricky Gray's TV was badly damaged in the quake. "[I] Could hear the quake coming about twenty seconds before I felt it."
Feilding New World.
Feilding New World.
Damage at a home in Opiki.
Damage at a home in Opiki.
Charlotte Robertson and Zaria Hemara were at Saddle Bridge, where the earthquake caused a landslide. "I was horrified to see a huge dust cloud spreading across the river as part of the cliff gave way. As the shaking subsided I grabbed my phone and tried to take photos of the dust cloud and the scarred cliff.”
Charlotte Robertson and Zaria Hemara were at Saddle Bridge, where the earthquake caused a landslide. "I was horrified to see a huge dust cloud spreading across the river as part of the cliff gave way. As the shaking subsided I grabbed my phone and tried to take photos of the dust cloud and the scarred cliff.”
A large cliff slip near Mangaweka caused the Rangitikei River to change colour.
A large cliff slip near Mangaweka caused the Rangitikei River to change colour.
One of two houses to lose chimney's on McGiffert St in Palmerston North.
One of two houses to lose chimney's on McGiffert St in Palmerston North.
The Greig family said: "This is one of the many cracks we found in the driveway near our front door. We live 15 minutes south west of Palmerston North".
The Greig family said: "This is one of the many cracks we found in the driveway near our front door. We live 15 minutes south west of Palmerston North".
Children being evacuated from a building in Palmerston North.
Children being evacuated from a building in Palmerston North.
Palmerston North's Leeds St resident Maria Dalziel said her fence toppled "like a house of cards".
Palmerston North's Leeds St resident Maria Dalziel said her fence toppled "like a house of cards".
Earthquake in Palmerston North. Douglas Jarrett, who was in the square edge building running a holiday programme, checks to see if there are any cracks in building.
Earthquake in Palmerston North. Douglas Jarrett, who was in the square edge building running a holiday programme, checks to see if there are any cracks in building.
Brenda Anderson tweeted this photo: "Damage at Pukaha Mt Bruce just after today's quake."
Brenda Anderson tweeted this photo: "Damage at Pukaha Mt Bruce just after today's quake."
Two chimneys on a street in McGiffert Street, Palmerston North.
Two chimneys on a street in McGiffert Street, Palmerston North.
Scrambled eggs!
Scrambled eggs!
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
Earthquake. A Hobbit eagle falls in front of the Billie Chu food outlet at the Wellington Airport.
A news crew takes video of the eagle that landed at Wellington Airport in the earthquake - thankfully not hurting anyone.
A news crew takes video of the eagle that landed at Wellington Airport in the earthquake - thankfully not hurting anyone.
Andy Burt tweeted this photo, writing, "Rock falls all along the Manawatu Gorge following the quake."
Andy Burt tweeted this photo, writing, "Rock falls all along the Manawatu Gorge following the quake."
Thankfully no one was hurt when the eagle came crashing down.
Thankfully no one was hurt when the eagle came crashing down.
Karen Monks of Masterton tweeted this picture of the contents of her pantry.
Karen Monks of Masterton tweeted this picture of the contents of her pantry.
Karen Monks of Masterton took this shot of her office, writing that it was "less fuzzy" than a previous photo now that her hands had stopped shaking.
Karen Monks of Masterton took this shot of her office, writing that it was "less fuzzy" than a previous photo now that her hands had stopped shaking.
Karen Monks of Masterton tweeted that she had "big cracks in every room" following the quake.
Karen Monks of Masterton tweeted that she had "big cracks in every room" following the quake.
@Femkesvs tweeted this picture of her bookshelf: "Well that was the bookshelf".
@Femkesvs tweeted this picture of her bookshelf: "Well that was the bookshelf".
Apparently no one was hurt when the eagle crashed at Wellington airport
Apparently no one was hurt when the eagle crashed at Wellington airport

Scientists are investigating links between yesterday's 6.2-magnitude earthquake and a nearby series of strong tremors which occurred in the past.

Dozens of significant aftershocks were forecast as unwelcome sequels to yesterday's quake that damaged homes, cracked roads, toppled cliffs and left thousands without power.

The Wellington Anniversary Day quake, which struck shortly before 4pm, was centred about 15 kilometres east of the rural Tararua town of Eketahuna at a depth of about 33km.

GeoNet spokeswoman Sarah Page said more seismometer would be sent to the Eketahuna region this week.

"Specifically, efforts are aimed at comparing the current earthquakes with a sequence of events that occurred to the north of Eketahuna in the early 1990s."

Four large earthquakes shook the region, in the south-east of the North Island, between 1990 and 1992.

Scientists were also looking at the possibility of a link to the ongoing Kapiti slow slip event - a slow release earthquake which is affecting an area spanning over 100km from Levin to the Marlborough Sounds.

The likelihood of a larger triggered event in the coming weeks is minor. However, it is possible and we should all take this opportunity to review our earthquake emergency plans," she said.

The most shaking from Monday's 6.2 quake was recorded in Woodville as about one quarter of acceleration due to gravity - or 0.26 g.

Strong shaking was also recorded on the Kapiti Coast, with up to 0.2g in Paraparaumu, while accelerations recorded in Wellington city were less than 0.05g.

By comparison, ground motions recorded during the recent Cook Strait earthquakes ranged up to 0.75g.

By 8.30pm last night, 8000 people had reported feeling the quake to Geonet.

GNS duty seismologist Caroline Little said yesterday's quake was caused by the Pacific tectonic plate "subducting" under the Australian plate, and could not be pinned on an individual fault line.

Late last year, GNS Science released a report showing a tsunami up to 35 metres high could cause as much devastation over Wellington and Napier as the 2011 waves caused in Japan.

Little confirmed the "worst case scenario" would be triggered by the same two plates that caused yesterday's quake.

However, unlike yesterday, when the epicentre was deep inside the Pacific plate, for a tsunami to be triggered the plates would have to clash at the "interface" of the two and be centred out to sea.

A larger quake would also be needed to trigger a tsunami, she said.

The report, by natural hazard scientist Graham Leonard, said waves could reach 15 metres above normal sea level in Wairarapa, Northland, Great Barrier Island, and parts of East Cape, but Wellington's steep valleys could amplify tsunami waves up to 35m, he said.

"No part of the New Zealand coastline is free from tsunami hazard," the report warns.

Little said yesterday's quake was different from two historic quakes in the area that caused serious damage.

A magnitude 8.2 quake on the Wairarapa Fault in 1855 remains the most violent in New Zealand since European settlement.

A 10-metre tsunami struck Palliser Bay on the south Wairarapa coast, flooded Porirua Harbour, and hit Titahi Bay and the Kapiti Coast.

In Wellington, a 4 metre to 5m tsunami swept over the isthmus between Lyall Bay and Evans Bay where Wellington Airport is now located..

In June, 1942, a 7.2 quake centred near Masterton shifted houses on their foundations and caused some roofs to collapse. Damage was widespread in he town and only a few buildings survived unscathed.

In Wellington, 100 city buildings were found to be seriously damaged, about 10,000 chimneys toppled and 5000 homes needed extensive repairs.

Little said yesterday's quake was more similar to a 6.4 quake centred near Weber, Tararua in May, 1990, that caused no major damage.

It was expected the next seven days would see another quake - possibly up to five - of magnitude 5-5.9.

The Dominion Post