Earthquakes - What is the Risk?

Earthquakes - What is the Risk?

Has the risk of earthquakes been overestimated in New Zealand?  The Christchurch earthquakes of 2010 and 2011 put a huge toll on the people of Christchurch but also a burden for the rest of New Zealand.  The question remains – “Are we now going too far to protect the lives of our people in future events?  Can we afford the cost?

The current Building Act of 2004 has a policy for Earthquake Prone Buildings (EPB’s).  Each individual council is required to have a policy for identifying and dealing with buildings defined as earthquake prone.  The minimum standard is specified as 33% of New Buildings Standard (% NBS).  That correlates to the strength 1/3 of the strength of a building built today to current building standards.  Most councils have taken 33% NBS as the minimum standard for giving differing time periods for owners to either strengthen their building or demolish to remove the hazard.

Regulators are currently preparing legislation to amend the Building Act with the EPB provisions likely to be amended.  It is likely that the new legislation will become more stringent and involve tighter timeframes and impose more cost onto commercial building owners.  This will come at a massive cost.  Estimates are there are over 1000 EPB’s in Auckland alone with an estimated cost of over $500M to strengthen.  With many of these buildings either outside the CPD of cities in suburbs such as Mt Eden, Balmoral, Te Aro or in provincial New Zealand towns such as Oamaru, Gisborne, Whakatane and Rotorua (to name a few) where rental returns are low and the cost of strengthening is uneconomic, where does this leave the future of these areas?

New Zealand needs its heritage and our buildings to define who we are, the struggles we have faced to forge our nation and we owe it to our forbearers to save the best examples for future generations to enjoy.

I believe that over the next 10 years we will see a huge change in our towns and cities.  Substandard heritage buildings with no heritage merit will disappear and will be replaced with modern structures that better cater for 21st century lifestyles.  A selection of heritage structures that either have architectural, or cultural merit or have historical significance will be retained and bought up to a good standard.  The government needs to consider ways to ease the pain for owners of these buildings with one option being tax breaks for commercial property owners completing seismic strengthening.

The risk of injury in earthquakes needs to be put into perspective.  With only two major earthquakes in New Zealand causing deaths in the past 100 years (Napier 1933 and Christchurch 2011) is the billions of dollars required to deal with the issue worth the investment?  Should market forces be left to determine what level of compliance is right for the safety of our people?

This thought leadership article is by Andrew Thompson, the Structural Engineering Manager at Harrison Grierson.

Back to HG Perspective