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Home » Is it safe to build across known fault lines?

GEOLOGICAL SOCIETY OF NEW ZEALAND Inc

Press statement, 16 March 2001

Is it safe to build across known fault lines ?

Planning rules covering building across known fault lines need urgent changes, according to scientists and engineers who specialise in earthquake hazards.

In a joint statement, the Presidents of the New Zealand Society for Earthquake Engineering (David Brunsdon) and the Geological Society of New Zealand (Simon Nathan) say that a recent report by the Parliamentary Commissioner for the Environment reveals deficiencies in the way the Resource Management Act and the Building Act deal with earthquake hazards.

The report "Building on the edge: the use and development of land on or close to fault lines" points out that few local authorities consider the vulnerability of buildings near fault lines.

The Commissioner's report points out that there is no existing technology that will prevent damage to buildings caused by fault rupture. For this reason it is unacceptable to site buildings on or close to active faults. Fault rupture is one of the most predictable and avoidable earthquake hazards.

"One of the worst examples is Wellington City, where a house up to 8m high can be built across the active Wellington Fault without restriction" Dr Nathan said. " By comparison, in California any building for human occupancy must be set back at least 15m from a known active fault."

According to the Resource Management Act, territorial authorities have responsibilities for avoiding and mitigating natural hazards, but few have incorporated information on known fault lines into their District Plans.

Information on earthquakes and mitigation measures on district plans often varies between adjacent councils, even where they share the same hazard.

Mr Brunsdon has been involved with reconnaissance teams who have visited earthquake-hit areas in many parts of the world. He pointed out that there had been major damage along faults that ruptured during earthquakes in Turkey and Taiwan in 1999, and it was only a matter of time before similar damage occurred in New Zealand.

The topic of building across active faults is to be discussed at the annual Conference of the New Zealand Society of Earthquake Engineering, to be held in Wairakei next weekend (March 23-25).

A copy of the report by the Parliamentary Commissioner for the Environment can be downloaded (pdf) from the GSNZ website.