Friday, July 13, 2012

Quake Safety, Stonehaven Slippery Slopes, Christchurch Quakes

Sat 14.07.12. Email reply to a USA Florida mate:

"They keep rolling on - shallow, crustal quakes, (5-20 km deep) unlike anywhere else in the world, with potent accelerations, horizontal & vertical. You're right, one can't anticipate or predict quakes & when they hit, we wonder, 'Is this the big one again, or do we dive under a table, or run for the door?' Quite a relief when it's over, once more. We've endured 10 000+ quakes in the last couple of years.

2-3 mags are rarely noticed, but 4 mag & above make us alert. We're good at estimating quake mags, then checking on Geonet website. In SA we watched out for people attacks. For the last couple of years in Christchurch we watch out for quake attacks. Seismologists will have to rewrite quake theory after Christchurch settles down.

As for scaremongering, Cantabrians have got blase about quakes, staying alert, but knowing when to watch it! 03.07.12, Taranaki district (N Island) had a mag 7 quake, 230 km deep, offshore, on a plate fault. Nearby Wellingtonians crapped themselves, little damage, but it felt like a mag 4 to me in Christchurch. Rest of NZ got in a tizz, but us lot, 'No worries mate.'

Christchurch authorities are demolishing all the crap bldgs, old & new, so eventually Christchurch will be one of the safest seismic zones in the world to live in - hopefully. Costs billions, including quake strengthened rebuild. CBD is still locked down in a military, red zone cordon, while high rise demolitions continue. Has enabled suburbs to boom with businesses relocated from the CBD.

Like you & hurricanes, we shrug off fear & sleep through many night quakes now. Some people can't stand it anymore & have left for 'safer' towns & cities. After the June 13 quake last year, I said to a Maori bloke, 'Despite quakes, we feel safer in NZ than when we lived in SA.'"

Post 22.02.11 quake, after more than a year of land zonings, CERA recently rezoned Port Hills white zone properties to red or green zones. CERA minister Brownlee's excuse for slow Port Hills zonings was the difficulties of geotech experts ascertaining hill slide, rock fall or cliff fall dangers. Any nitwit could see living on a steep hillside, under a cliff, or on a cliff top was dangerous.

Images, quake damaged Port Hills Rd:


14.07.12. Quake damaged, boarded house, Port Hills Rd



14.07.12. Port Hills Rd view of quake rock fall hazard housing

166 Port Hills properties were still white zoned, in limbo, to be rezoned by October 2012. I was curious to see what all the fuss was about. As I hadn't looked too closely at cliff dwellings, I drove to still white zoned Stonehaven Tce & Lucas Ln, Hillsborough, below slippery cliffs, where I'd already wandered post 22.02.11 quake on the flats.

Images, quake damaged Alderson Ave:


14.07.12. Cnr Port Hills Rd / Alderson Ave


"Tce" rang alarms, as Terrace housing I'd seen in quaked Christchurch were either quake-stuffed hillside housing, or quake-stuffed riverside housing. I parked my car on Port Hills Rd by quake damaged, boarded houses & wandered past an Alderson Ave corner board which read:

             Millennium 2000
   Communities Christchurch Street
           and Garden Awards
This plaque commemorates the special
     efforts made by the residents of
 Alderson Avenue which was selected
       as the most attractive street
        within the boundary of the
          Spreydon / Heathcote
            Community Board


14.07.12. Millennium 2000, Garden Awards board, cnr Port Hills Rd / Alderson Ave


14.07.12. Quake damaged roof, Alderson Ave


14.07.12. Quake damaged, boarded house, Alderson Ave


14.07.12. Alderson Ave view of quake rock fall hazard housing



I wandered up Alderson Ave where posh housing had crept up Port Hills, On my right Lucas Ln houses were quake damaged below loess cliffs. Alderson Ave veered left uphill as Stonehaven Tce which was also quake damaged. Above houses at Lucas Ln & Stonehaven Tce there was a devil's mix of gullies, rocky bluffs & thick vegetation. Below Stonehaven Tce houses were slippery loess cliffs, mostly covered in vegetation.There were also houses below Stonehaven Tce loess cliffs on my left. What a development mess!


14.07.12. Alderson Ave view of quake rock fall hazard housing



14.07.12. Alderson Ave view of quake loess slip hazard & rock fall hazard housing




Council planning stupidity: Below stony gullies, bluffs & a reservoir, Stonehaven Tce new, posh housing spotted the hillside, vegetation gaps between houses. Stonehaven Tce had retaining walls above & below the road. Stonehaven houses were sandwiched between rocky bluffs above & loess cliffs below. New houses were threatened by rock fall above the road & new houses were threatened by loess slip below the road.

Anyone buying & building on top of a cliff, or below a cliff was dumb. Council was dumber allowing that to pass.



14.07.12. Quake damaged house below loess cliff, Alderson Ave. Quake rock fall hazard housing above






Adding to the devil's mix, a concrete drain covered in metal grills, was at the end of a gully by Aldersons Reserve & Lucas Ln, where the drain went underground down Alderson Ave.

Images, quake damaged Lucas Ln:

  

14.07.12. Quake trashed house below slippery loess cliff, Lucas Ln


















14.07.12. Quake trashed house below slippery loess cliff, Lucas Ln












 


14.07.12. Alderson Ave view of quake trashed housing below slippery loess cliff, Lucas Ln


Images, quake damaged Alderson Ave:


14.07.12. Drain, Aldersons Reserve, Alderson Ave


14.07.12. Alderson Ave view of Aldersons Reserve, drain & drain ditch, above Lucas Ln, quake trashed housing



In Aldersons Reserve a gum grove sucked up gully water, some gums chopped down. Below gums were creamy loess lumps, which had bounced a quake-distance from loess cliff collapse. Above the reserve, geotech experts had sprayed & chopped out vegetation, showing several huge cracks - looked like a fault line to me. I didn't venture up the cracks, as I feared a quake would vanish me.


14.07.12. Alderson Ave housing in danger of quake rock fall & loess slip








14.07.12. Quake cracked curb & road, Alderson Ave

Cracks went uphill & were about 3 m wide & deep in places, widening as they went uphill to an old farm property. Further up the cracks I saw geotech experts had placed pink-tipped, wooden stakes in cleared ground, like hedgehog bristles, to check hillside slip & loess collapse, above Lucas Ln.


14.07.12. Loess clods flung from loess cliff by quakes, Aldersons Reserve


14.07.12. Aldersons Reserve, quake loess slip hazard above Lucas Ln








14.07.12. Quake rock fall hazard & gully drainage hazard above Alderson Ave & Lucas Ln




What a mess! Dangers of flooding, rock fall, bluff collapse, loess cliff collapse & loess slip, all above Lucas Ln & Stonehaven Tce.

It was scandalous that Council planners, consenters, surveyors, architects, engineers, developers, builders had gone ahead with housing development on steep hillsides. Like Seabreeze Cl, Bexley swamp development, Stonehaven hillside development should never have been allowed.

Port Hills posh houses with million dollar views, doomed to red zoning, meant ratepayers would be forced by CERA to share payouts to Port Hills red zoners. CERA's cosy dealing with Council meant extortion of $100 million from poor ratepayers to punish Council planning stupidity & pay rich ratepayers for building / buying / repairing dangerous Port Hills properties. (3News)

Rationale for that extortion was that Council was responsible for ameliorating Port Hills rock fall hazards on Council land above housing developments.

That extortion didn't benefit red zoners on the flats, with their months earlier red zoning, but was belatedly, quietly decreed by CERA to benefit Port Hills rich red zoners.

A closer look at Lucas Ln by Aldersons Reserve: Several quake trashed, abandoned, boarded, tarped houses, protected from rock fall & loess fall by shipping containers. While I snapped, a woman stopped her car, demanding, "Are you just taking a look?" I explained.

Alderson Ave took a sharp, uphill turn, by a farm gate & a 3 pronged gum tree & became Stonehaven Tce. Metal STONEHAVEN lettering on a stone wall announced entry to the new uphill development. Rocky bluffs loomed above Stonehaven development.

Images, quake damaged Stonehaven Tce:


14.07.12. Housing in danger of quake rock fall hazard, Stonehaven Tce




14.07.12. Post quake road repairs to quake cracked / slipped roadside, Stonehaven Tce


14.07.12. Quake cracked, part repaired roadside & curb, Stonehaven Tce



14.07.12. Quake damaged retaining wall, slipping away from quake slipped Stonehaven Tce







14.07.12. Quake damaged pavement, fence & gate slipping downhill, Stonehaven Tce


Stonehaven Tce: Housing was in danger of rock fall from above & slipping downhill, as some houses were build on loess below the road. All along the road, downhill side, cracked concrete curbs & repaired road cracks showed where quakes had already caused slippage.


14.07.12. Concrete retaining wall, quake rock fall hazard above, Stonehaven Tce


14.07.12. Post quake repairs to quake slipped pavement & roadside, Stonehaven Tce




14.07.12. Stonhaven Tce, loess cliff house, post quake view of Glenelg Spur & Hillsborough



14.07.12. Stonehaven Tce, loess cliff house, post quake view of Glenelg Spur, Hillsborough & Opawa



14.07.12 Post quake repairs to slipped roadside & pavement, Stonehaven Tce





14.07.12. Concrete retaining wall below housing, quake rock fall hazard above, Stonehaven Tce

Images, quake damaged Stronsay Ln:


14.07.12. House retaining wall, in danger of quake collapse, above Stronsay Ln, off Stonehaven Tce





14.07.12. Post quake repairs to quake slipped retaining wall, Stronsay Ln


14.07.12. Stronsay Ln, quake cracked curb & loess cliff view over Hillsborough & Opawa






14.07.12. Loess cliff, slip hazard & quake rock fall hazard by new housing, Stronsay Ln


14.07.12. Loess cliff lot, quake loess slip hazard, Stronsay Ln



14.07.12. Post quake, Stronsay Ln view of Glenelg Spur & Port Hills Rd




14.07.12. Stronsay Ln, zoom view of quake trashed, red zone, abandoned Christchurch CBD

 
Retaining walls had separated from the road in a slow slide. Never mind housing damages. One posh house sported an architect's board in a window. Housing development & real estate boards hung hopefully on roadside fences too.


14.07.12. Developers sign, quake rock fall hazard hillside, Stronsay Ln



14.07.12. Quake damaged house on quake rock fall hazard hillside, Stronsay Ln









14.07.12. Post quake, Stronsay Ln view of Glenelg Spur


14.07.12. Post quake, Stronsay Ln view of Opawa


14.07.12. Quake damaged, abandoned house, Stronsay Ln





14.07.12. Quake slipping house, loess cliff top, Stronsay Ln


14.07.12. Void under quake slipping house, loess cliff top, Stronsay Ln




14.07.12. Bare loess ground, quake slipping house, loess cliff top, Stronsay Ln


There were empty lots between Stonehaven houses. Below the road in empty lots, one could see bare loess. Some houses were abandoned, others occupied. One house had a huge void below concrete stairs. The black void extended below the hillside house. The new house had no garden. Weed-killer killed vegetation, exposed loess soil on the property.

Stronsay Ln fork, downhill off Stonehaven Tce: I wandered to the end of Stronsay Ln, past a concrete, cracked retaining walls & builders' rubbish, stacked roadside, past overgrown lots, the reservoir louring above. At Stronsay Ln end, rock fall boulders perched on top of a rock-smashed, retaining wall.


14.07.12. Quake crack between retaining wall & pavement, Stronsay Ln


14.07.12. Real estate sign, quake cracked road & retaining wall, Stronsay Ln




14.07.12. House in danger of quake rock fall hazard, Stronsay Ln. See rocks secured by steel cables






14.07.12. Builders rubbish, Stronsay Ln end



 

14.07.12. Bare lots, loess cliff top, Stronsay Ln end



14.07.12. Concrete retaining wall, Stronsay Ln end


14.07.12. Quake rock fall damage, concrete retaining wall, Stronsay Ln end

Below the reservoir, bluff rocks above the last Stronsay Ln house were strapped with steel cables, stopping rock fall.

There were lovely views over Hillsborough, Opawa & Glenelg Spur housing, towards hazy CBD. My 10x zoom camera took good pics of red zone, abandoned CBD, about 10 kms away, still military cordoned, 17 months post 22.02.11 quake. Demolition cranes loomed above abandoned high rises.

You wouldn't catch me buying a house anywhere near Stonehaven in Hillsborough.

Sun 22.07.12. I drove to Moncks Bay, as I wanted to hear testing of the new tsunami warning system, built post quakes, with sirens on top of power poles along the coast. Over the last week, I'd seen digital signs by QE11 Park & by McCormacks Bay causeway informing residents about testing of new tsunami warning sirens at 11 am, Sun 22.07.12. A first for Christchurch.

Images, quake damaged McCormacks Bay Causeway:


22.07.12. Tsunami siren testing board, McCormacks Bay Causeway


While Leah & I waited for the siren, I checked out quake damaged Cliff St & Emily Hts by Moncks Bay. Several houses were quake damaged along Cliff St, a house demolition site near the end.

The end house, built on red volcanic rock, was horizontally cracked at window height. The rock on which the house was built was cracked vertically & horizontally. Another boarded, cliff side house had a red rock in its driveway. "A wise man built his house upon a rock..." song wasn't true in Christchurch.

Images, quake damaged Cliff St:


22.07.12. Quake damaged garden wall, Cliff St


22.07.12. Quake damaged housing, Cliff St 


22.07.12. Quake damaged housing & house demolition site right, Cliff St


22.07.12. Quake damaged house on loess hillside, Cliff St


22.07.12. Quake rock fall below loess cliff, Cliff St

Images, quake damaged Emily Hts:


22.07.12. Quake trashed house on volcanic rock, cnr Cliff St / Emily Hts











22.07.12. Quake split volcanic rock, Emily Hts



Emily Hts was another pre quake, housing development, not as far gone as Stonehaven, Hillsborough, but also built on a devil's mix of loose loess & volcanic rock on a steep hillside.


22.07.12. Wooden retaining wall & quake damaged, part repaired roadside, Emily Hts. Moncks Bay & Southshore spit beyond


Emily Hts zig-zagged up the hillside past wooden retaining walls, to the top where another house was built. So far no other pre-quake houses were built on Emily Hts. The road was trashed - roadside cracks, where the hillside was slipping due to quakes. Houses above & below Emily Hts were quake damaged, tarped & boarded.


22.07.12. Quake trashed, part repaired roadside, Emily Hts. Loess cliffs beyond



There were lovely views of Pegasus Bay, Moncks Bay, Avon / Heathcote Estuary mouth, Southshore spit, quake stunted Shag Rock & shipping-container-protected Clifton corner. But lethal quake conditions.
 

22.07.12. Cliff St view of quake trashed Emily Hts development. Houses below & above loose loess cliffs



Over the last week I'd seen new adverts trumpeting virtues of bldg repair businesses, wanting to cash in on post quake repairs & rebuilds. An advert on the back of a ute listed all repairs the contractor would do. Top of the list: EARTHQUAKE REPAIRS.

Metropol BUY BUILD INVEST, Issue 11, July 2012 publication had many repair / rebuild adverts. One caught my eye:

"STAKE CONSULTING LTD...

GROUND PENETRATING RADAR (GPR) [For checking quake voids below bldgs].
 Do you think you have underlying problems with your concrete floor?...

SLAB JACKING
Solution and repair for lifting driveways, paths and floors.
Filling of voids below concrete slabs.

CONCRETE CRACK REPAIRS
Don't allow water ingress through your concrete cracks this winter.
Epoxy Pressure Injection..."

Post quakes, I'd seen many tilt slab bldgs with quake cracked walls, epoxy glued. Soon EQC would be castigated for shoddy repairs, like faulty jack & pack of pile foundations. Given quake damages & shoddy EQC repairs, I wouldn't buy any bldg in Christchurch.

As for the tsunami warning siren, at 85 db it wasn't loud enough. We were parked at Beachville Reserve by Avon / Heathcote Estuary. Leah heard the siren faintly in our car. As I wore a hearing aid, I had to get out of the car & hardly heard the siren. Council needed to increase siren volume, or $550 000 would be wasted. 

Luke didn't even hear the siren in a South New Brighton house, near South New Brighton School. Why did Council spend half a million+ dollars on a siren system for Pacific regional quakes & ignore Pegasus Bay quakes? No tsunami danger from Pegasus Bay Fault huh?

Wed 31.10.12, CERA press release, Brownlee: "All 190 000 properties in greater Christchurch now have a zoning...

The vast majority of the over 7 860 property owners in the residential red zone have already chosen a buyout option and are in the process of selling their properties to the Crown... "

The residential red zone buyout was a NZ govt land grab of choice, riverside properties & choice, hillside properties. Later on NZ govt would land grab choice, red zone CBD properties for its Blueprinted CBD. NZ govt's tame, geotech engineering firm, Tonkin & Taylor did the land zoning. Then NZ govt in the form of CERA land grabbed choice properties. There were no controls on Tonkin & Taylor.

The final 8 Lucas Ln properties were green zoned, finalizing zoning of residential properties in Christchurch. Green zoned! Lucas Ln housing was stuffed! CERA & Council would remove landslip material above Lucas Ln housing. CERA & Council would share the cost of loess removal & securing the slippery slope. Nothing was said about why Council allowed housing development below slippery loess cliffs in the first place.

By Jan 2014 the slippery loess slope above Lucas Ln was secured.

Content & pics Copyright Mark JS Esslemont.

See City's share of Port Hills cost known next month (The Press / Stuff Co).

See Tsunami warnings go unheard (The Press / Stuff Co). 

See Residential land zoning complete (CERA press release).

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