Monday, 22 July 2013

Earthquakes & Density: Will We Ever Learn?

Guest post by Hugh Pavletich

With the 6.5 magnitude Marlborough earthquake events beginning a little after 5pm Sunday 20th July 2013,and the accompanying fore-shocks and after-shocks radiating in to New Zealand’s capital city Wellington some 56 kilometres away (USGS Information), Wellington’s central area and commuter train service was shut down, and the high-density central city turned into a ghost town.

A lesson to take from this and earlier earthquakes: High-density urban centres do not perform well in earthquakes on the “resiliency front.”

And a question for planners to ponder: What would or could happen if this significant and shallow earthquake event occurs in Wellington Harbour?

Following the 11 kilometre deep  7.4 magnitude Darfield event some 38 kilometres outside Christchurch on 4 September 2010, seismologists were generally of the view the worst was over, and aftershocks of diminishing intensity could be expected for another year or so.

Based on this professional assurance, most in the Christchurch area were rather pleased with themselves, and how they had coped with the 4 September 2010 event. Particularly pleased with themselves were the Authorities, from whom there was much political grand-standing.

Then about 5 months later on 22 February 2011, the shallow 6.3 magnitude earthquake stuck  (6 kilometres deep 7 kilometres from CBD) at the Lyttelton Tunnel.  And on 13 June 2011, a 6.4 magnitude event occurred in the Redcliffs, some 9 kilometres from the CBD at a depth of 7 kilometres.

Seismologists had remarkably little to say following these events.

Within months following the February event, the engineering profession, in conjunction with the Royal Society, released an important report The Canterbury Earthquakes. This report illustrated from accelerometer readings throughout the city the intensity of the g-forces experienced in specific locations.

The great untold story of Christchurch has been how the low and light structures in low-density areas coped remarkably well (often well outside their design limits), provided the ground underneath them remained stable.

In contrast, the high density and aged CBD did not cope at all well.

What the 22 February 2011 earthquake event failed to destroy in the central area, the Authorities did, by banning essential and timely  redevelopment and restoration.

Time was always a critical factor.

Instead – devoid of elementary commercial and urban development knowledge, the public bureaucracies at local and central level saw it as an opportunity to arrogantly engage in surreal “visions.”

The politicians were simply the parrots. (These issues have been extensively covered by the writer within Christchurch: The Way Forward (incorporating hyperlinks to earlier articles), and just recently, within a New Zealand National Business Review Opinion Christchurch: The political shambles.)

Since the first earthquake event 4 September 2010, near 3 years ago now, there have been some 13,500 tremors in the greater Christchurch area, as the Canterbury Quake Live website illustrates.

Urban Planner Joel Cayford explained with Councils Fudge Christchurch Seismicity, around the time of the release of the Royal Society report, how urban planners had ignored earthquake risks.

Earthquake risks had been well understood by those involved in urban issues for decades – particularly engineers and developers. (The Engineering School at Canterbury University had for decades following World War 11, been regarded as one of the lead research institutions international on earthquakes.)

In 1996, the TV3 Inside New Zealand "Earthquake!" documentary, provided a snap-shot of the understanding by that time.

With the follow-on Wellington earthquake events, one is reminded of the song by Royal Wood (Youtube Video) "Will We Ever Learn" … with the lyrics …

Will we ever learn?
From what we’re feeling
Will we ever learn?
As sorrows deepen

Will you ever see?
Just what you mean to me

Will we ever learn?
It all but breaks us
Will we ever learn?
When it forsakes us

Will you ever say?
How much you love me
Will you ever say?
No one above me

h my we’re wasting time
Oh my we’re wasting time
Oh yes we’re wasting time again
Will we ever learn?
Will we ever learn?

Will we ever be?
Behind the curtain
Will we ever be?
In a life that’s certain

Hugh Pavletich is the Coordinator for Cantabrians Unite the co-author of the Annual Demographia International Housing Affordability Survey, and the webmaster for the archival website  Performance Urban Planning.

1 comment:

  1. Frank Lloyd Wright wrote an essay in 1922, entitled "Experimenting with Human Lives", regarding the building of anything other than low density development in earthquake prone regions. Of course his whole career was dedicated to the architecture and urban design and landscaping of low density urban form.

    He would seem to have been influential in California and interestingly, Japan, on this point. The Japanese have consistently done their best in spite of their very high population for their land space, to keep their urban form as un-concentrated as possible. Wendell Cox wrote somewhere recently that Japan has a lot of its urban areas that achieves lower density than the UK's equivalents, in spite of having a lot more people.


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