A Californian scientist has warned that future buildings
erected across New Zealand will never be earthquake-proof and
labelled Christchurch rebuild plans "unrealistic.''
University of California professor Norman Abrahamson gave the
stark warning during the third day of hearings of the Royal
Commission inquiry into the Canterbury earthquakes.
The commission is examining the cause of building collapses,
especially during the February 6.3 magnitude quake which
claimed 182 lives, and how such a disaster can be avoided in
During a live video conference, the international earthquakes
expert questioned several aspects of a key government report
produced after the tragedy.
The adjunct professor of civil engineering at Berkeley said
GNS Science plans to make buildings across New Zealand safer
during earthquakes go much further than those in his home
state of California, which sits astride the infamous San
He said that New Zealand society must debate how much they
are willing to pay to make buildings as safe as possible.
Professor Abrahamson said: "In the end, it all comes down to
risk, and what is acceptable risk. In the earthquake business
we don't do anything where we design for the worst case and
give people zero risk. There will always be a risk.''
He criticised the section on minimising risk in the GNS
Science report, `The Canterbury Earthquake Sequence and
Implications for Seismic Design Levels', in his international
The expert asked: "What are the acceptable risk values? I
think the (GNS) guidance document is brief on this _ and I
did get some additional information from Dr McVerry (GNS
principal scientist) on where the risk numbers come from. But
in my view, these risk numbers are unachievable as written in
the report. Your goal is a bit too low and very difficult to
He said that California - especially San Francisco, which was
devastated by the magnitude 7.9 earthquake of 1906 which
killed up to 3000 people, and a 6.9 magnitude shake in
1989 - had a much more "realistic'' building code.
Pointing to the high aversion to risk of loss of life in the
GNS report, Abrahamson said: "We are nowhere near those
numbers in California. We're at double the high end of that
He added: "In trying to think what is appropriate we have to
start to think what is realistic numbers.
"It's not for me to decide, it's a broader social issue - do
you want to have more safety at a higher cost, or do you
accept the kind of risk numbers that are acceptable around
Prof. Abrahamson said New Zealand's existing building code
was consistent with international standards.
He said the government needed to ask if they wanted to go
above that level for added safety to try to cover more of
these earthquakes on unidentified faults in the future.
After his evidence, Abrahamson took part in a panel
discussion with GNS scientists.
The first of 11 hearings in the inquiry, sitting at St
Teresa's Parish church hall in Riccarton, Christchurch, was
due to be completed today, but is expected to run over into
The commission is set to hear evidence until next March
before presenting its findings to the government by April 11.
Evidence on the collapse of the PGC building, where 18 people
died, is scheduled to start on November 28, while the CTV
building, which killed 115 people, is down to be heard in
- Kurt Bayer of APNZ