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Thursday, June 23, 2011

Tremor upgraded to magnitude 5.4

Last updated 13:25 22/06/2011
 
A magnitude-5.4 aftershock slammed into Halswell and Lincoln but cuased little further damage to Christchurch's red zone or the city's water and sewerage infrastructure.

The quake that hit the region at 10.34pm yesterday was this morning upgraded to a 5.4 at a depth of 8km, up from what had been reported as a 5.3 at 12km.

It was followed by 10 aftershocks overnight, with the biggest being a magnitude 4.4 shortly before 3.30am.

A Halswell New World staff member said the store sustained more damage in last night's violent aftershock than it did on February 22 or June 13.

The staffer, who did not want to be named, said "everything fell off every shelf". The store lost "an extensive amount of stock", with wine and juice bottles smashed in the aisles.

About a dozen staff came in to clean up the mess for four hours last night and the supermarket opened on schedule at 7.30am today.

The main jolt was first thought to be centred 10km west of Akaroa, but GNS seismologist John Ristau said this morning that records now showed it was centred just 10km south of Christchurch City, near Halswell.

Halswell resident Debbie King said it felt like "a truck slammed into the house" when the 5.4 aftershock hit.

King said her Westlake Drive house sustained more damage last night then it did last week or in February.

"A 5.3 seems very low because it was one of the strongest I have ever felt out here," she said.

Last night's quake caused further damage in Christchurch's cordoned red zone, Canterbury Earthquake Recovery Authority (Cera) spokeswoman Catherine Delore said.

"Some additional masonry has come down, some of those cracks ... have widened a bit, but it hasn't changed the overall demolition picture in town,'' she said.

"There's a bit more brickwork and glass down on the ground as well.

"And obviously, access to it remains restricted to the same degree that it was following the June 13 earthquakes."

Delore said she had no information to suggest that any of the central-city "indicator" buildings had moved further.

Cera said the June 13 quakes had caused "significant additional damage" in the red zone, including the Hotel Grand Chancellor twisting 75 millimetres more, while the Copthorne Hotel in Durham St had twisted a further 50mm.

Christchurch City Council water and waste manager Mark Christison said no further damage to the city's water and waste infrastructure had been identified after last night's jolt.

Ristau said it appeared another small fault below Banks Peninsula had ruptured, causing the sharply felt magnitude-5.4 quake.

"You are sitting on hard volcanic rocks there and when it breaks it tends to break very strongly, producing a lot of shaking and energy."

By 11.30pm, the GeoNet website had more than 1000 "felt reports" from as far afield as Paraparaumu and Invercargill.

Four from Hornby and Upper Riccarton considered it was heavily damaging, with 13 classifying it as damaging and more than 100 as slightly damaging.

Lincoln resident Farhad Dastgheib said the quake pushed his bed around violently.

"We heard a rumble and thought 'not again'. It didn't last as long as last week's quake but still felt scary. The aftershocks keep coming."

The quake was the strongest since magnitude-5.7 and 6.3 shocks hit Christchurch last week.

Christchurch Boys' High School has closed for engineering checks today after the night of shakes.

While Christchurch Airport was carrying out runway checks after the quake, four flights were diverted to Auckland, an airport spokeswoman said. 

Two inbound trans-Tasman Air New Zealand flights, NZ888 from Sydney and NZ804 from Brisbane, were diverted to Auckland.

Two other flights, Pacific Blue's DJ82 from Brisbane and Jetstar's JQ191 from the Gold Coast, were diverted to Auckland but had planned to return to Christchurch at 2.05am, as long as the runways were clear.

- The Press and The Dominion Post

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